People love argue over what “counts” as bluegrass. While such debates may be fun, they miss the point; Our view is that bluegrass music doesn’t come with clean edges or a written rulebook. The edges are fuzzy because the music is rich and still evolving, because different regions and scenes carry their own norms, and because the people inside a tradition are always re-drawing its outline in real time.

Our view is that bluegrass should be a large tent:

It is large in time — eight decades since Bill Monroe’s classic Blue Grass Boys lineup (Monroe, Earl Scruggs, Lester Flatt, Chubby Wise, and Howard Watts) cut “Heavy Traffic Ahead” in 1946, with new bluegrass made every year since. It is large in space: there are scenes in Japan, the Czech Republic, Australia, and across Europe. And it is large in approach. We have been at jams in Europe where a harmonica player and a jazz clarinetist sat in alongside the fiddle. We have been at festivals in Colorado where pickers played Guns N’ Roses on banjos and mandolins. We have heard a circle of music students at two in the morning, lovingly working out the Scooby-Doo theme song. All of that is bluegrass, in some sense.

To be inclusive is the right move musically and culturally. The core goal of the Picker’s Guide is to help our users grow as musicians. There is no better way to do that than to learn new things. A great strength of our genre is the ever-expanding horizon; the more we learn, the more we discover. Culturally, it should go without saying that music is perhaps humanity’s most universal and collaborative creation. Music is about bringing people together, not about drawing arbitrary lines that divide us.

The Picker’s Guide rule

Our rule for inclusion in The Picker’s Guide is one question:

Could this song plausibly get called at a bluegrass jam?

That test welcomes Monroe and the Stanleys and Flatt & Scruggs and their contemporary trad descendants. It welcomes the jazz-inspired compositions of the David Grisman Quintet, the beautiful fiddle tunes of John Hartford, the avant-garde work of Béla Fleck and the Punch Brothers, Ola Belle Reed’s heartbreaking mountain ballads, and Gillian Welch’s modern songwriting masterpieces. It welcomes the gospel quartets, the murder ballads, the train songs, and the moonshine ballads that fill out the working canon. It welcomes the Beatles covers and the Bob Dylan songs the genre has absorbed and the country and outlaw classics that have become and integral part of the songbook. The test is deliberately broad because the music is rich and varied.

Mapping the territory

Inside the large tent, the music has a clear center — and a set of substyles arranged around it, each leaning toward a different neighbor.

The core is traditional bluegrass — the first-generation vocabulary that came out of Monroe’s lineup and the Stanley Brothers and Flatt & Scruggs, and everything that’s built directly on that vocabulary since. Most of what we now call mainstream modern bluegrass also sits in the core: The Bluegrass Album Band, Ricky Skaggs and Kentucky Thunder, the Lonesome River Band, the Earls of Leicester, Doyle Lawson and Quicksilver, The Del McCoury Band, The Johnson Mountain Boys, Hot Rize, Larry Sparks and the Lonesome Ramblers and many more — bands whose claim on the word “bluegrass” is uncontested. Just outside the core, leaning slightly toward country and old-time, sit the brother-duet tradition (the Monroe Brothers, the Louvins, the Delmores) and it’s contemporary examples. Also just outside the core is prodigious bluegrass-gospel canon — close enough to feel central to the genre, but with distinct musical fingerprints that earn its own place on the map.

Moving outward, the music blends with neighboring traditions, and each direction has produced music that are unmistakably bluegrass and unmistakably influenced by something else. Old-time and mountain music in one direction — older fiddle-tune repertoire, modal tunings, and the pre-bluegrass string-band aesthetic the founding generation grew out of. Country and honky-tonk in another — Nashville song forms, steel-and-shuffle phrasing, the commercial-country tradition bluegrass has shared studios and songwriters with for decades. Folk and the singer-songwriter tradition in another — narrative lyric primacy, simpler harmonic settings, the acoustic-revival sensibility. Jazz in another — improvisation, extended harmony, chamber-acoustic ambition, and the Django-and-Grappelli gypsy-jazz lineage that came in through Grisman and Tony Rice. Rock in another — drums and electric textures, the festival jam-band energy that lives on the genre’s most extroverted edge. (Blues isn’t on this map as a separate axis because it isn’t a neighbor — bent-note phrasing and twelve-bar forms were absorbed into the founding canon directly, alongside the Anglo-Celtic material. It’s in the DNA, not on the perimeter.)

Most published bluegrass scholarship treats the genre chronologically — Bill Monroe and the founding generation, the folk-revival era, the newgrass and progressive expansions, the 1980s neo-traditional revival, the contemporary scene. That chronology is useful and we cover it in the History section. What it doesn’t do is give a working listener a map of the music as it exists right now: the styles a contemporary band can choose between, the vocabulary each style works in, and the artists who exemplify each.

That map is what this essay attempts. To our knowledge no published source has laid it out in quite this form. There are precedents — Robert Cantwell’s Bluegrass Breakdown (1984) gives interpretive portraits of the founding figures; Neil Rosenberg’s Bluegrass: A History (1985, 2005) gives the chronology; Wikipedia maintains a flat subgenre list; Chris Pandolfi of the Infamous Stringdusters wrote a “Two Worlds of Bluegrass” essay for No Depression dividing the contemporary scene into traditional and progressive camps. None of them resolves into a usable taxonomy of styles in the working musician’s sense. This is our attempt, acknowledging that any taxonomy is going to draw arguments.

Traditional bluegrass

The founding-era template: Bill Monroe and the Blue Grass Boys, Flatt and Scruggs, the Stanley Brothers, Jim and Jesse, Reno and Smiley, the Osborne Brothers in their early years, Jimmy Martin, Mac Wiseman. All operating in the same instrumental vocabulary — guitar, mandolin, banjo (three-finger style), fiddle, upright bass — with three-or-four-part vocal harmony built on chord tones. The harmonic vocabulary is I, IV, V plus the dominant V7, with occasional secondary moves (the major II as setup for V) and the flatted seventh as a modal color. Tempos run from slow-ballad through standard-uptempo to banjo-feature breakdowns at the high end. The repertoire mixes Appalachian ballads, Anglo-Celtic broadside material, gospel hymns from the Stamps-Baxter and Brumley songbooks, twelve-bar blues-derived songs from the Monroe canon, and original compositions in the same vein.

Traditional bluegrass is not over. The form is being actively worked by living musicians, and a self-conscious traditional-revival pole emerged in the 1980s and is still going. The Bluegrass Album Band recorded six volumes of self-consciously traditional bluegrass between 1981 and 1996. The Earls of Leicester (assembled by Jerry Douglas in 2013 to play Flatt and Scruggs material) won the Grammy for Best Bluegrass Album for their self-titled debut and three consecutive IBMA Entertainer of the Year awards (2015-2017). The hard-traditional jam scene in the rural South still works from this template.

Modern/Southern / “Mash” Bluegrass

A note on placement: Mash sits inside the bluegrass core on our diagram, not on a perimeter axis — it’s the contemporary commercial-mainstream wing of trad bluegrass, not a substyle leaning toward a neighbor. It gets its own section because the scene has consolidated enough vocabulary over the last three decades to be worth treating at length.

A hard-driving, downbeat-emphasizing scene that emerged in the 1990s and consolidated through the 2000s and 2010s. “Mash” is documented in cited scholarship: Thomas Cassell’s 2021 MA thesis at East Tennessee State University, In Seeking a Definition of Mash: Attitude in Musical Style, identifies it as a sonic style with specific musical features — rhythm, downbeat treatment, melody, modality — that “worked its way into the genre as a descriptor of a certain sound” beginning in the 1990s. The Bluegrass Situation’s working definition is more compact: “that driving, head-bobbing, modern iteration of traditional ‘grass that refuses to commit to a minor or major third.” Bluegrass Today’s vocabulary checklist defines mash as “a medium tempo, downbeat-heavy style of bluegrass, usually in the key of B (with capo), as popularized by The Lonesome River Band.”

Key bands of the foundational era: Lonesome River Band, IIIrd Tyme Out (Russell Moore), Joe Mullins & the Radio Ramblers, Junior Sisk, Blue Highway, Mountain Heart in its early years, Audie Blaylock, Cherryholmes. The sonic profile: guitar in G position, capo to wherever the singer needs (capo 4 to B is the signature mash position), banjo and mandolin pushing hard on the offbeats, a wall-of-sound studio production where each instrument and voice gets a dedicated microphone. The harmonic vocabulary mostly stays inside traditional bounds, though flatted and modal melodies are common. The arrangements are often tighter and more sophisticated than 1940s-50s trad.

The polished, mainstream-commercial wing of the same scene runs through Alison Krauss & Union Station — Krauss’s 27 Grammys (for years the most of any female artist in history; only Beyoncé has since passed her) and her work as a producer of bluegrass-leaning country records have set the era’s commercial ceiling. Bluegrass Situation includes AKUS in the mash lineage; other writers place her separately as “contemporary mainstream.” Either way, the bands working in this wing — Krauss, Dailey & Vincent, Rhonda Vincent and the Rage, Sister Sadie, the post-Tony-Rice configurations of the bluegrass mainstream — are operating in the same general harmonic and rhythmic zone as the foundational mash acts, with more polished production and country-leaning vocal aesthetics. Modern Southern is bluegrass’s commercial center in the festival and IBMA circuit. The audience is large, the standards are high, and the harmonic and rhythmic conservatism is intentional.

The brother-duet thread

Brother duets appear on our diagram as a substyle dot just outside the core, leaning toward country and old-time. The tradition also cuts across most of the substyles above. This section is the longer look — the thread of family-blood vocal duets has been continuous since before bluegrass existed. The pre-bluegrass duets — covered in detail in History Chapter 1 — gave bluegrass its close-harmony vocal vocabulary. The five canonical pre-bluegrass brother duets, in roughly chronological order:

• The Blue Sky Boys (Bill and Earl Bolick, Hickory, NC, debuted RCA Bluebird 1936) — sacred songs and ballads, the clearest and most restrained harmony of the era.
• The Delmore Brothers (Alton and Rabon, Elkmont, Alabama, recording from December 1933) — modern swing-influenced; “Brown’s Ferry Blues” and “Nashville Blues” entered the bluegrass canon.
• The Callahan Brothers (Walter and Homer, North Carolina) — middle ground between the Bolicks and the Delmores; heart songs, tragic romances, train songs.
• The Monroe Brothers (Bill and Charlie, recording for Bluebird February 1936 onward) — the most dynamic of the group: fast tempos, high pitched singing, Bill’s piercing mandolin leads. Sixty sides between 1936 and 1938. Bill founded the Blue Grass Boys the year after the split.

Within bluegrass: Jim and Jesse McReynolds (the longest-running professional brother duet in country music history, 1947 to 2002), the Stanley Brothers (as a vocal duet within their band), the Osborne Brothers, and — the modern continuation — the Gibson Brothers (Eric and Leigh, IBMA Entertainer of the Year 2012 and 2013), Michael Daves’ collaborations with Chris Thile and Jacob Jolliff, Eli West and Cahalen Morrison, and many others.

Why brother-duet harmony sounds the way it does has been studied empirically. Identical twins share vocal-fold geometry, vocal-tract dimensions, and acoustic timbres that produce measurably similar voice quality (Decoster et al., Voice similarity in identical twins, 2000; Van Lierde et al., Journal of Voice, 2005). Full siblings raised together share enough of this geometry, plus a lifetime of imitative prosody, to produce the distinctive blend that bluegrass listeners hear as “blood harmony.” The brother-duet stack is the bluegrass close-harmony tradition’s structural seed.

Gospel bluegrass

A distinct sphere, structurally and institutionally. The IBMA awards a separate Gospel Recorded Performance of the Year. The genre has its own scene, its own canonical artists, and a vocal architecture — the four-voice quartet of lead, tenor, baritone, and bass — that differs from the three-voice stack of the standard bluegrass trio. The repertoire is also distinct, drawing on the Stamps-Baxter songbook publishing tradition, Albert Brumley’s catalog (“I’ll Fly Away,” “Turn Your Radio On”), traditional hymnody, and the Carter Family religious material.

The founding generation built gospel into the heart of bluegrass from the start. Bill Monroe cut substantial gospel sessions throughout the 1940s and 1950s — “Wicked Path of Sin,” “Walking in Jerusalem Just Like John,” “A Voice from on High,” “Working on a Building,” “I’ll Meet You in the Morning” — and used the quartet form to reach four-voice arrangements his trio configurations couldn’t. Flatt & Scruggs made gospel central to both their stage shows and their catalog (“Give Me Flowers While I’m Living,” “Take Me in the Lifeboat,” “Give Mother My Crown”), with the 1960 Columbia album Songs of Glory devoted to it entirely. Jimmy Martin built a gospel set into every show and recorded the form steadily across his Decca years (“Singing All Day and Dinner on the Ground,” “Aim for the Sky,” “Lord, I’m Coming Home”). His contributions to the Nitty Gritty Dirt Band’s 1972 Will the Circle Be Unbroken — including his lead on “I Saw the Light” — became one of the album’s emotional anchors. The Stanley Brothers‘ gospel records on Mercury and King defined the modern bluegrass-gospel template for the next half-century.

The lineage continued. The Lewis Family (Lincolnton, Georgia — “First Family of Bluegrass Gospel,” 1951–2009). Doyle Lawson & Quicksilver, whose Rock My Soul in 1981 was a landmark modern gospel-bluegrass project; Lawson was inducted into the IBMA Bluegrass Hall of Fame in 2012 and received a National Heritage Fellowship in 2006. Joe Mullins & the Radio Ramblers, Dailey & Vincent (Jamie Dailey came up in Quicksilver). The lineage traces back through the Stamps-Baxter Southern Gospel quartet style to 19th-century shape-note singing; Lawson explicitly synthesized white and Black gospel-quartet traditions into the bluegrass setting.

The musical form is its own thing. A few features set bluegrass gospel apart from the rest of the genre.

Waltz time is common. Many of the canonical numbers are in 3/4 — “Amazing Grace,” “Beautiful Star of Bethlehem,” “In the Garden,” the slow-ballad version of “Will the Circle Be Unbroken,” and a long list of older hymns. The three-quarter sway carries a kind of emotional weight in this corner of the genre that the bluegrass 4/4 doesn’t.

Four-voice harmony with the bass on the bottom. The added bass voice gives the quartet a low end the bluegrass trio doesn’t have, and lets the four parts move more independently than the close-stacked tenor-and-baritone of a standard arrangement. Voices cross, the baritone takes a counter-line, the bass walks underneath instead of just doubling the root.

Call-and-response and stop-time. Lead singer calls a line and the quartet answers; the chorus inverts the relationship; the bass takes a featured line under sustained upper voices; the band drops out for a vocal-only tag. A cappella verses are common, and full a cappella arrangements have their own honored place in the canon.

In live performance many bluegrass bands play a gospel set or at least one gospel song somewhere — even acts whose primary identity is secular. Gospel is a vocabulary bluegrass-at-large draws on, not only a separate sub-genre.

Mountain ballad

The song-and-ballad wing of bluegrass with roots deep in the Appalachian narrative tradition. Where String band (below) lives in the fiddle-tune-and-dance vocabulary, Mountain ballad lives in the vocal-and-song vocabulary: ballad forms (some of them older than the genre by centuries), narrative lyrics, drone-leaning harmony, frequent use of the flatted seventh as structural color rather than passing chord, modal melodies in dorian or mixolydian, and a vocal aesthetic — “high lonesome” — that came to bluegrass from the same well of older Appalachian singing.

The phrase “high lonesome” originated in old-time, not in bluegrass. John Cohen coined it in 1959 in Daisy, Kentucky, when he first heard the modal-pentatonic banjoist and singer Roscoe Holcomb sing on a porch outside town. Cohen used the phrase as the title of his 1963 documentary about Holcomb. Six years later, Mike Seeger applied “high lonesome” to bluegrass tenor singing in his Folkways liner notes for Mountain Music Bluegrass Style. The phrase has read as bluegrass-specific in mainstream press ever since, but its origin is the older Appalachian singing the bluegrass tenors drew on.

The bluegrass acts who lived squarely in this zone: the Stanley Brothers’ Columbia and King Records-era recordings of British broadside ballads (“Pretty Polly,” with its origin in the 1727 Gosport Tragedy; “Little Maggie”) and the modal “Man of Constant Sorrow” that, four decades later, would become the most-cited single song in the O Brother, Where Art Thou? soundtrack. Ralph Stanley‘s post-Carter Clinch Mountain Boys work, including his unaccompanied “O Death” on the same soundtrack — the deepest single expression of the high-lonesome aesthetic in the contemporary canon. Bill Monroe’s modal originals like “Get Up John” and “Wheel Hoss.” Larry Sparks‘s mountain-blues phrasing through five decades of recording on Rebel and Rounder. Hazel Dickens‘s harder-edged work with Alice Gerrard.

The songwriting bridge from old-time: Ola Belle Reed, the Ashe County-born, Maryland-based clawhammer banjoist and singer whose original compositions — “High on a Mountain,” “I’ve Endured,” “Over Yonder in the Graveyard” — entered the bluegrass repertoire and stayed. Del McCoury’s early-1970s recording of “High on a Mountain” — he cut it before Reed recorded it herself — remains the standard bluegrass reading; the song has been covered widely across the genre since. Reed lived squarely on the old-time side of the genre line, but her songbook is in the bluegrass canon. The fuller account is in our old-time chapter.

The defining sonic features: vocal-led arrangements (the song is the point, not the breaks); fewer chord changes than mainstream trad bluegrass; modal melodies in dorian, mixolydian, or pure pentatonic; drone-leaning arrangements that sit on the tonic and move through sparser changes; the flatted seventh as a structural color, not a passing tone. Many of these songs are also crooked — built on uneven measure counts that don’t resolve to a steady 4/4 — a marker of the older song tradition that bluegrass mostly straightened out but never entirely abandoned. Ralph Stanley, until his death in 2016, insisted that what he played was “old-time mountain music, not bluegrass.” This is the substyle he was claiming.

String band

The fiddle-tune-and-dance wing of bluegrass — the substyle that maintains the strongest aesthetic ties to the pre-bluegrass commercial string-band tradition of the 1920s and 1930s. Where Mountain ballad lives in vocals and narrative songs, String band lives in instrumental tunes, ensemble-led playing, and a dance-floor or jam-circle aesthetic.

The pre-bluegrass source: the commercial string-band recordings of the 1920s and early 1930s. Charlie Poole and the North Carolina Ramblers (whose 1925 Columbia single “Don’t Let Your Deal Go Down” sold a hundred thousand copies in a year and modeled the working ensemble shape that bluegrass would later refine); the Skillet Lickers (Gid Tanner, Riley Puckett, Clayton McMichen, Fate Norris — the loudest, raucous-est dance band of the era); the Carter Family of Maces Spring, Virginia; the Stoneman Family; Mainer’s Mountaineers; and dozens of regional ensembles whose 78-rpm records Harry Smith would later anthologize. These bands shared instrumentation (fiddle, banjo, guitar, sometimes mandolin or autoharp) with what bluegrass would become, but their ensemble model — everyone playing the melody together, or alternating lead and rhythm without the formal solo-sequence convention — was a different beast. Bluegrass took the instruments. The Scruggs three-finger banjo and the soloist-and-accompaniment ensemble model came later.

There is honest fuzziness at this edge. “String band” as a term is more often used for old-time bands than bluegrass bands — bands like Foghorn Stringband and Uncle Earl consider themselves old-time, not bluegrass (see our old-time chapter for the parallel scene) though there is clearly enough musical and cultural overlap to welcome them into the bluegrass tent and the bluegrass campground is filled with people playing in this style.

The defining sonic features: often more of instrumental focus; fiddle-tune-heavy repertoire (older traditional tunes, less original material); fiddle and clawhammer as core parts of the ensemble; ensemble-based interplay rather than strict soloist-and-accompaniment; medium-to-fast tempos suitable for dance or square-dance contexts; instrumental virtuosity in the service of the ensemble rather than the solo break.

Country bluegrass

The country-leaning wing of bluegrass — the substyle whose vocal aesthetic, repertoire, and song forms borrow most heavily from commercial country music, and whose recordings have historically charted in both country and bluegrass categories. Country bluegrass acts cover Hank Williams, Merle Haggard, Lefty Frizzell, Johnny Cash, and George Jones; they write originals in country-song forms; and their singers often sound as much like honky-tonk lead singers as like high-lonesome bluegrass tenors.

The bluegrass anchor: Jimmy Martin, “the King of Bluegrass,” who left Bill Monroe’s Blue Grass Boys in 1954 (he had been Monroe’s lead singer since 1949) and formed his own band, the Sunny Mountain Boys, in 1955. Martin’s self-described style was “Good ‘n Country” — commercially oriented, crowd-pleasing bluegrass with simple harmonies, catchy melodies, and a strong rhythm propelled by his own guitar playing. He recorded 138 titles for Decca between 1956 and the mid-1970s; a handful of them — “Ocean of Diamonds,” “Sophronie,” “Widow Maker,” “Sunny Side of the Mountain” — charted on the country music charts of the 1950s through 1970s, an unusual achievement for a bluegrass artist. Martin’s banjo player from 1956 to 1960 was a young J.D. Crowe; the lineup he led with Crowe and mandolinist Paul Williams was, by Martin’s own later assessment, the greatest band he ever fronted.

The country-pop crossover wing of this same scene ran through the Osborne Brothers‘s Decca/MCA period (1963 onward). The Osbornes added electric instruments, drums, and full Nashville Sound production to bluegrass arrangements; “Rocky Top” (1967), written by Felice and Boudleaux Bryant, became their signature song and a country radio hit. Their work split the bluegrass world — traditionalists thought they had gone too far toward Nashville — but their commercial reach made them the most-heard bluegrass act of the late 1960s.

The country-and-bluegrass two-way street continues. Ricky Skaggs grew up playing bluegrass with Ralph Stanley, spent the early 1980s as a mainstream country star with eleven #1 country hits, and returned to bluegrass in 1997 with Kentucky Thunder. Vince Gill moved from bluegrass into country and back. The Hank Williams catalog, the Merle Haggard catalog, the George Jones catalog — these are in the working bluegrass repertoire and have been since the founding generation. (For the singer-songwriter side of country-and-bluegrass crossover — the Prine, Townes, Earle, Cash, Haggard songbook entering bluegrass via cover — see Country-folk songwriter, below.)

The defining sonic features: country-style vocal aesthetic (closer to a honky-tonk lead than to a high-lonesome tenor); country song forms (verse-chorus structures, often with bridges); melodic emphasis over modal-ballad emphasis; willingness to add country-music production elements (the Osbornes added electric bass and drums; Krauss’s Union Station added a soft-edged commercial polish); and a repertoire that draws as heavily from the commercial-country songbook as from the trad-bluegrass canon.

Country-folk songwriter

The substyle defined by repertoire rather than sound — the body of songs by country-folk singer-songwriters that has, over the last fifty years, entered the working bluegrass canon by way of cover. The substyle has a central figure and a deep cast around him.

One of the central figures is John Hartford. Born in New York City in 1937 and raised in St. Louis, Hartford moved to Nashville in 1965 to work as a session musician and staff songwriter. In 1967 he wrote “Gentle on My Mind,” which Glen Campbell took to #1 country and then to pop in 1968; the song won four Grammys and became one of the most-performed songs in BMI’s licensing history. The royalty stream from “Gentle on My Mind” funded Hartford’s quiet pivot away from Nashville commercial-country and back toward acoustic-string-band music a few years later. Aereo-Plain (Warner Bros., 1971), recorded with Norman Blake, Vassar Clements, Tut Taylor, and Randy Scruggs, would be cited as the foundational moment of newgrass (see Progressive bluegrass, below). Hartford spent the rest of his career as a country-and-bluegrass crossover figure — a licensed Mississippi riverboat pilot, a stage performer in a derby hat tap-dancing on a sheet of plywood, and the songwriter whose catalog the bluegrass world has worked through more thoroughly than any other singer-songwriter’s. Sam Bush’s 2022 Radio John: Songs of John Hartford on Smithsonian Folkways is the most direct contemporary acknowledgment of Hartford’s centrality. Hartford died on June 4, 2001.

Another major contributor to the bluegrass-side songbook is Townes Van Zandt (Texas, 1944-1997). Townes wasn’t a bluegrass musician, but his songs — “Pancho and Lefty,” “If I Needed You,” “Snowin’ on Raton,” “White Freightliner Blues,” “To Live Is to Fly” — have entered the working bluegrass repertoire at a rate that puts him second only to Hartford in this substyle. The Lonesome River Band, the Steeldrivers, Tim O’Brien, and many others have covered Townes material since the 1990s; Willie Nelson and Merle Haggard’s 1983 #1 country cover of “Pancho and Lefty” cemented the song’s status, and the bluegrass world picked it up from there.

The broader canon. John Prine (“Paradise,” “Angel from Montgomery”; the Seldom Scene took “Paradise” into the bluegrass canon in 1973). Steve Earle (whose 1999 The Mountain with the Del McCoury Band was a wholly-bluegrass tribute to Bill Monroe, Grammy-nominated for Best Bluegrass Album). Johnny Cash (“Folsom Prison Blues,” 1955, a bluegrass-jam standard for sixty years). Merle Haggard (“Mama Tried,” 1968, widely covered). Bob Dylan (“Don’t Think Twice, It’s All Right,” 1963). Gordon Lightfoot (“Early Morning Rain,” 1965 — Tony Rice recorded so much Lightfoot material that Rounder eventually compiled Tony Rice Sings Gordon Lightfoot in 1996; in the liner notes Rice observed that “Lightfoot’s tunes were very adaptable to a bluegrass or string-band genre”). John Denver (whose “Country Roads,” 1971, is one of the most-called songs at any bluegrass jam, anywhere). Kris Kristofferson. Guy Clark. Each generation of bluegrass musicians takes more of this material into the working repertoire.

The substyle’s distinction from neighbors: where Country bluegrass covers commercial country writers in country-leaning arrangements with country-style vocal aesthetics, Country-folk songwriter is more lyric-driven and less honky-tonk — the material is the singer-songwriter canon, where the lyric is doing the heavy lifting. Where Folk bluegrass is about specific bands (the Country Gentlemen, the Seldom Scene) and their approach, Country-folk songwriter is about the songbook those bands and many others draw from. The substyle has no defining sonic features beyond the bluegrass instrumental vocabulary applied to material from a specific writers’ canon.

Folk bluegrass

The bluegrass substyle that grew out of the Washington, D.C. area in the late 1950s and 1960s, drew its repertoire from the folk-revival songbook (Dylan, Lightfoot, Prine, James Taylor, the Anglo-Celtic ballad tradition the Cambridge and Greenwich Village folkies were also working), and polished the bluegrass ensemble for the college coffeehouse rather than the rural festival. The substyle has two foundational bands. They share a mandolinist.

The Country Gentlemen formed on July 4, 1957, in the suburbs of Washington, after an automobile accident sidelined the bluegrass musician Buzz Busby and his banjoist Bill Emerson called a pickup band together to keep Busby’s regular gig at a Bladensburg, Maryland club. The pickup band — Emerson on banjo, the Louisiana-born guitarist Charlie Waller, and a young DC-born mandolinist and tenor singer named John Duffey — stayed together. Duffey did not want the band to play the standard trad-bluegrass set. He spent hours at the Library of Congress folksong archive looking for new repertoire; he raided Protestant hymnals; he embraced Bob Dylan’s songs early and openly; he treated bluegrass as a vehicle for whatever material he found interesting. The band’s early Folkways records — Country Songs Old and New (1960), Folk Songs and Bluegrass (1961) — signaled the new approach. By the mid-1960s, the Country Gentlemen were the bluegrass band that played college folk clubs in Georgetown and Cambridge as comfortably as they played Bean Blossom.

The Seldom Scene formed in Bethesda, Maryland, in 1971, with Duffey on mandolin again. The other four founders all held weekday jobs in the DC area: John Starling was a physician, Mike Auldridge was a graphic artist at the Washington Star, Ben Eldridge was a mathematician, and Tom Gray was a cartographer at National Geographic. The band rehearsed Monday nights and played weekly Tuesday-night residencies in DC clubs (first the Red Fox Inn, then the Birchmere) for the next quarter-century. The day-job arrangement meant they could choose material on aesthetic grounds rather than commercial — their albums covered John Prine (“Paradise”), Steve Young (“Lonesome, On’ry and Mean”), James Taylor, Bob Dylan, Gordon Lightfoot, Phil Ochs, Eric Andersen, and Paul Siebel alongside the trad-bluegrass and Stanley Brothers material their audience also expected. The first three albums — Act I (1972), Act II (1973), and Act III (1973) — on Rebel Records established the template: tight quintet arrangements, Auldridge’s pioneering dobro phrasing, Starling’s clear singing voice, and a repertoire that read more like a coffeehouse setlist than a Carlton Haney festival bill. All five original members were inducted into the IBMA Hall of Fame in 2014.

What Folk bluegrass keeps from the bluegrass mainstream: the ensemble (Scruggs banjo, mandolin, dobro, guitar, upright bass), the solo-sequence convention, the tenor-harmony stack. What changes: the repertoire (folk-revival, songwriter, acoustic-singer material rather than trad-bluegrass canon and country charts) and the audience (college students, public-radio listeners, the broader folk-revival crowd rather than the Southern festival circuit). The substyle overlaps significantly with what later got called Progressive bluegrass — the Country Gentlemen are sometimes called “the fathers of modern bluegrass” and credited with starting the progressive-bluegrass movement; the Seldom Scene’s style was sometimes filed under “newgrass” — but the DC sound is the part of that movement that kept the bluegrass ensemble and the trad vocal arrangement most intact, even as the song choices opened up.

The defining sonic features: polished quintet arrangements (often with dobro instead of fiddle); folk-revival repertoire; a clear-singing, often country-tenor lead voice (Charlie Waller, John Starling) rather than a high-lonesome mountain tenor; a deliberate aesthetic of refinement and arrangement over the festival-circuit drive of mainstream bluegrass.

Acoustic Americana

The substyle just at the bluegrass edge: contemporary acoustic singer-songwriters who emerged from or share players with the bluegrass scene but who work in a quieter, lyric-focused, indie-folk register that the bluegrass world doesn’t generally call its own. The substyle’s center of gravity is the Americana awards and the public-radio circuit rather than IBMA and the festival circuit. The instrumentation overlaps significantly with bluegrass (mandolin, guitar, dobro, fiddle, sometimes banjo and upright bass), but the ensemble model, the song forms, and the audience are different.

Two of the substyle’s pioneers are Gillian Welch and David Rawlings. Welch was born in 1967, raised in Los Angeles, trained at Berklee, and moved to Nashville in the early 1990s. Her 1996 debut Revival, produced by T Bone Burnett, established the template: spare two-guitar arrangements (Welch’s strummed acoustic and Rawlings’s lead guitar lines, both on small-bodied vintage instruments), close two-part harmony with Welch’s slightly behind-the-beat lead vocal, songs that read as character-portrait fiction rather than ballad-tradition narrative, and Appalachian-revival aesthetic markers (modal melodies, sometimes drone-leaning, often capoed high). Time (The Revelator) (2001) and The Harrow & The Harvest (2011) became the substyle’s reference recordings. Welch and Rawlings have won Grammy Awards in country and folk categories; their work bridges bluegrass, old-time, country, and indie-folk audiences but does not sit squarely in any one of them.

The next generation built on that foundation. Watchhouse (formerly Mandolin Orange, renamed in 2021), the North Carolina duo of Andrew Marlin (mandolin, vocals) and Emily Frantz (fiddle, harmony), have been recording since 2010 in a similarly spare two-instrument-plus-harmony register, with Marlin’s songs working much of the same Appalachian-melodic and modal-harmonic vocabulary as Welch. Sarah Jarosz (born in Texas in 1991, started recording professionally as a teenager) won her first Grammy at twenty-two and has won four to date; her solo work covers acoustic-singer-songwriter material with bluegrass-tradition instrumental skill on mandolin, banjo, guitar, and octave mandolin. I’m With Her (Jarosz with Aoife O’Donovan and Sara Watkins, formed for tour in 2014 and recorded its debut See You Around in 2018) is the contemporary supergroup configuration. Andrew Marlin‘s solo records push deeper into the instrumental old-time fiddle-tune tradition than his Watchhouse material does. Tim O’Brien‘s solo career, Molly Tuttle‘s work outside the Golden Highway band, and Aoife O’Donovan‘s solo material all sit in this orbit.

The distinction from neighboring substyles: where Folk bluegrass (the Country Gentlemen and Seldom Scene wing) keeps the full bluegrass ensemble and the solo-sequence convention while choosing folk-revival material, Acoustic Americana drops more of the bluegrass-specific features — the small-ensemble or duo configuration replaces the quintet; the song forms are singer-songwriter rather than ballad-and-instrumental-break; the ensemble model is duo-with-occasional-collaborator rather than the bluegrass band. Where Country-folk songwriter is the source-songbook substyle — the body of older songwriter material that bluegrass musicians cover — Acoustic Americana is the substyle making the songwriter material now: its acts are primarily original-songwriters whose songs will be the next generation’s covers.

The substyle sits, honestly, more outside than inside the bluegrass tent. Welch, Watchhouse, Jarosz, and Marlin would generally not introduce themselves as bluegrass musicians, and the IBMA does not generally nominate them in bluegrass categories. They live in the broader Americana world that bluegrass shares borders with. What keeps them in our diagram: working bluegrass musicians play their songs at jams, they came up through the bluegrass scene (Tuttle was the first woman to win IBMA Guitar Player of the Year in 2017; Jarosz came up through the IBMA Kids on Bluegrass program; Marlin spent years on the bluegrass festival circuit before Watchhouse leaned more songwriter-folk), and the line where bluegrass ends and Americana begins is genuinely fuzzy. The category has no standing journalistic label; we use it editorially.

Progressive bluegrass

The bridge generation and what followed. The substyle name newgrass originated in the early 1970s; progressive bluegrass is the umbrella that came to absorb it and the subsequent half-century of bluegrass acts who kept the acoustic ensemble while opening up the harmonic, rhythmic, and repertoire vocabularies the genre had inherited.

The founding generation. New Grass Revival — Sam Bush, Curtis Burch, Courtney Johnson, Ebo Walker; later John Cowan, Pat Flynn, and Béla Fleck — coined the term and gave the movement its name. The founding moment is widely cited as John Hartford‘s Aereo-Plain (Warner Bros., 1971); Sam Bush has said, repeatedly, that “without Aereo-Plain (and the Aereo-Plain band) there would be no newgrass music.” NGR formed the same year. The Country Gentlemen and the Seldom Scene are the parallel earlier figures, working a similar opening-of-repertoire problem from the DC folk side (see Folk bluegrass, above).

The newgrass innovation was to keep the bluegrass instrumental vocabulary and apply it to non-bluegrass material — rock songs, jazz tunes, longer-form jam structures, electric bass, fuller harmonic vocabulary including major sevens and minor sevens, freer instrumental improvisation drawn from jazz and rock more than from the melodic-paraphrase tradition of trad bluegrass. NGR as a working band dissolved at the end of 1989; the term and the ethos persisted.

The substyle also has an instrumental-composition wing that runs parallel to the vocal-and-song side. Béla Fleck‘s Drive (Warner Bros., 1988) — Fleck banjo, Sam Bush mandolin, Tony Rice guitar, Stuart Duncan fiddle, Jerry Douglas dobro, Mark Schatz bass — opened the era’s instrumental-supergroup moment with an album of Fleck originals played by the deepest acoustic-instrumental band of the decade. Strength in Numbers‘s 1989 The Telluride Sessions (MCA Nashville) — Sam Bush mandolin, Béla Fleck banjo, Jerry Douglas dobro, Mark O’Connor fiddle, Edgar Meyer bass — followed a year later, with each of the seven tracks composed by a different pair of the five players. (Both records are sometimes filed under “new acoustic” in older journalism, but the bluegrass-supergroup ensembles and the writing-by-progressive-bluegrass-musicians origin put them squarely on the progressive side of the line we draw between the two substyles — see New Acoustic, below, for the contemporary instrumental melodic-mandolin tradition that descends from a different lineage.) The post-Telluride supergroup configurations — the Bush-Douglas-O’Connor-Meyer collaborations, Béla Fleck’s chamber projects — carry the instrumental-composition wing of progressive bluegrass forward.

The contemporary wave. By the 2020s, a generation of progressive-bluegrass acts had matured to fill arena tours and Grammy ceremonies: Molly Tuttle & Golden Highway (Crooked Tree won the 2023 Grammy for Best Bluegrass Album; City of Gold won the same award in 2024); Sierra Hull, who in 2016 became the first woman named IBMA Mandolin Player of the Year and went on to win the award five years running — her records, from Weighted Mind (Rounder, 2016, Fleck-produced) through 25 Trips (Rounder, 2020) and A Tip Toe High Wire (Concord, 2024), span the instrumental-composition wing and the contemporary singer-and-band model; Crooked Still (Aoife O’Donovan, Greg Liszt, Brittany Haas, Tristan Clarridge, Corey DiMario), whose cello-and-banjo configuration ran through the 2000s before its members fanned out across the contemporary acoustic-music landscape; the Punch Brothers (whose harmonic ambition and chamber-jazz orientation place them squarely in this lineage). What they share with their newgrass elders: an acoustic bluegrass ensemble at the center, plus the willingness to add electric instruments, drums, jazz-and-rock harmonic vocabulary, longer-form arrangements, and material from outside the trad-bluegrass canon.

The distinction from neighbors: where Dawg / Spacegrass drew bluegrass into an improvised chamber-jazz idiom; where New Acoustic works the contemporary instrumental melodic-mandolin tradition outside the bluegrass-ensemble model; where Jamgrass pushed the substyle’s expanded vocabulary toward rock-festival improvisation, Progressive bluegrass is the umbrella that contains the harmonically-and-rhythmically-expanded but still-recognizably-bluegrass-ensemble center of the modern genre. A useful musical-citizenship test: a band that has won or been nominated for the IBMA Bluegrass Album of the Year or the Grammy Best Bluegrass Album is operating within the substyle, even when the music itself reaches well past trad-bluegrass conventions.

New Acoustic

The contemporary instrumental melodic-mandolin tradition — composed acoustic instrumental music descending from the tunes-and-melodies axis that Tony Rice, Mike Marshall, and David Grisman’s less-jazz-leaning material opened up in the late 1970s and 1980s. Where Progressive bluegrass centers on bluegrass songs with extended vocabulary, and Dawg / Spacegrass works the improvised jazz-fusion register, New Acoustic lives in composed, instrumental, melody-forward acoustic music — tunes-and-melodies as the basic unit, with structural sophistication that distinguishes them from the older fiddle-tune tradition (the String band substyle, above).

The substyle’s center of gravity is the melodic-mandolin tradition: John Reischman‘s solo work and his band the Jaybirds; Andrew Marlin‘s solo instrumental records (Buried in a Cape, 2018; Witching Hour, 2021; Fable & Fire, 2023); Mike Marshall‘s long instrumental career from his Modern Mandolin Quartet and Choro Famoso work onward; Matt Flinner‘s trio and quartet records; the contemplative side of Tony Trischka‘s banjo work. The contemporary ensemble incarnation is Hawktail — the all-instrumental quartet of Brittany Haas (fiddle), Paul Kowert (bass), Jordan Tice (guitar), Dominick Leslie (mandolin) — whose music sits squarely in the chamber-acoustic-instrumental zone.

The defining sonic features: instrumental focus (no vocals, or very secondary); melodic primacy (the tune is the foreground, with arrangement and rhythm-section work in support rather than as solo-rotation backing); composed structures, often with sophisticated harmonic moves (modal mixture, secondary dominants, irregular phrase lengths); duo, trio, or quartet ensemble model rather than the bluegrass quintet; tempos ranging from contemplative-slow to dance-tune-fast but rarely the breakdown-blistering speed of mainstream bluegrass.

Vocal-side artists adjacent to this scene — Watchhouse, Sarah Jarosz, Aoife O’Donovan — sit in Acoustic Americana (below) rather than here. New Acoustic is fundamentally an instrumental substyle. Strength in Numbers and the 1989 Telluride Sessions, sometimes filed under “new acoustic” in older journalism, sit in Progressive bluegrass (above) under our taxonomy — that record is the instrumental-composition wing of progressive, with the bluegrass-supergroup ensemble model intact.

Dawg / Spacegrass

Progressive bluegrass’s jazz-leaning descendant, known by two co-existing names. David Grisman coined “Dawg music” for his hybrid of bluegrass instrumentation with Django Reinhardt and Stéphane Grappelli swing, Brazilian choro, and chamber-classical writing. The Dawg nickname came from Jerry Garcia, who started calling Grisman “Dawg” in the early 1970s when they were playing together in Old & In the Way; Grisman adopted it for the music. The originating record is The David Grisman Quintet (Kaleidoscope, 1977), with Grisman on mandolin, Tony Rice on guitar, Darol Anger on violin, Todd Phillips on second mandolin, and Bill Amatneek on bass. Tony Rice‘s parallel project — the Tony Rice Unit, beginning with Manzanita (Rounder, 1979) and developed through Mar West, Still Inside, and Backwaters (Rounder, 1982) — carried the same vocabulary forward into what Rice called “spacegrass.” Rice’s publishing company was named Spacegrass Music. Both terms refer to the same substyle territory: acoustic chamber-jazz fusion played on bluegrass instruments. Béla Fleck and the Flecktones (1989 onward) pushed the lineage further into electric jazz fusion. Andy Statman’s three collaborations with Grisman (1983, 1995, 2006) extend it into klezmer-and-bluegrass territory.

The sonic profile: instrumental focus, jazz harmonic vocabulary (m6, m7, altered dominants, modal jazz colors), swing rhythm rather than the bluegrass drive, ensemble interplay foregrounded over featured-soloist arrangement, chamber dynamics.

The songbook also crossed over. Django Reinhardt and Stéphane Grappelli’s 1930s Quintette du Hot Club de France recordings — “Minor Swing,” “Nuages,” “Djangology,” and the broader Reinhardt catalog — entered the acoustic-string-band repertoire through Grisman and Tony Rice, who covered the material on stage and in the studio across the 1970s and 1980s. By now Reinhardt tunes sit alongside Monroe instrumentals as standards a progressive-bluegrass or dawg-leaning jam circle can fall into, and adjacent swing-era jazz standards like “Sweet Georgia Brown” and “All of Me” travel the same path. The bluegrass mainstream picks up less of this material than the substyle’s edge does, but the edge has been bilingual since Grisman’s first quintet.

Jamgrass

The substyle has a clear origin point: Old & In the Way, the 1973–74 bluegrass band that put Jerry Garcia on banjo, David Grisman on mandolin, Peter Rowan on guitar and lead vocals, Vassar Clements (and earlier Richard Greene) on fiddle, and John Kahn on bass. The band played about eighteen months of regional concerts in California and Oregon and recorded the live album that bears the name (Round Records, 1975) — for many years one of the best-selling bluegrass records in history. Garcia, who had played banjo before he played electric guitar and was a lifelong bluegrass listener, brought the same harmonic curiosity and extended-improvisation aesthetic he was bringing to the Grateful Dead in parallel. Grisman brought the chamber-jazz vocabulary that would become Dawg music a few years later. The combination — bluegrass repertoire and instrumentation played with West Coast rock-and-jam sensibility — is the seed every subsequent jamgrass band has grown from.

The Grateful Dead never made a bluegrass album. They did make a habit of dropping bluegrass-and-country covers into rock sets — “Friend of the Devil,” “Brokedown Palace,” “Ripple,” “Big River,” “Cumberland Blues” — and the harmonic-and-improvisational permission slip Garcia’s playing represented (take a bluegrass tune, stretch it past four minutes, vamp on a mode for the back half of a section, segue between songs without stopping) passed directly into the working jamgrass scene that followed.

The contemporary scene built on that foundation. Yonder Mountain String Band (founded 1998 in Nederland, Colorado), Leftover Salmon (Boulder, 1989), Greensky Bluegrass, the Infamous Stringdusters, Railroad Earth, and — the contemporary torchbearer — Billy Strings, whose live sets carry Dead repertoire as load-bearing material. Hot Rize, in their original Boulder period, are often cited as the prototypical architects of the harmonic-expansion side: effects pedals on banjo, electric bass, deliberate stretching of trad-bluegrass form. The musical formula is bluegrass instrumentation at the core, with extended improvisations, modal vamps, spontaneous transitions between songs, festival-shaped repertoire, and — sometimes — a rock-backbeat sensibility, though most jamgrass bands still tour without a drummer.

One often-overlooked fact: even though jamgrass acts pull rock-festival audiences and inherit rock-band performance habits, most of them tour without a drummer. Billy Strings, Greensky, Yonder Mountain, the Infamous Stringdusters, the SteelDrivers, and Trampled by Turtles all carry only the standard bluegrass acoustic instrumentation in their regular touring band. Greensky’s Paul Hoffman has described his band as “a drum-less rock band.”

The harmonic vocabulary is broad — modal vamps, jazz colors, the full progressive-bluegrass palette — but the instrumental palette stays mostly acoustic-traditional.

Stomp clap

The substyle on the diagram’s farthest old-time-and-rock edge — past the boundary where bluegrass musicians would still call it bluegrass, into the early-2010s indie-folk-rock wave that used bluegrass-derived instrumentation in rock-pop arrangements. The IBMA does not nominate these acts. The bluegrass festival circuit does not book them. Working bluegrass musicians do not generally consider them part of the genre. They sit on the diagram because their instrumentation and aesthetic borrowed enough from bluegrass that mainstream music journalists, in roughly 2009 through 2014, frequently described them as bluegrass — and because the gap between what those journalists meant and what the bluegrass world means is itself part of the story this guide is trying to tell.

The defining acts. Mumford & Sons formed in London in 2007; their 2009 debut Sigh No More and 2012 follow-up Babel made banjo-led pop-rock briefly into a mainstream top-40 phenomenon. The Avett Brothers, from Concord, North Carolina, had been working a louder folk-punk-meets-bluegrass register since the early 2000s; their breakthrough came with I and Love and You (Rick Rubin-produced, 2009). The Lumineers, formed in 2005 in the New York area and relocated to Denver, hit with their self-titled debut and the single “Ho Hey” in 2012. Of Monsters and Men (Iceland), The Head and the Heart (Seattle), Edward Sharpe and the Magnetic Zeros, and a longer list of regionally-launched acts all worked the same broad zone.

At the bluegrass-adjacent end of the same wave: Old Crow Medicine Show (Nashville, formed 1998, breakthrough with “Wagon Wheel” in 2004) and Trampled by Turtles (Duluth, Minnesota, formed 2003). Both work in fully acoustic bluegrass-derived instrumentation — no kick drum, no group hand-claps — with high-tempo string-band aesthetics and bluegrass-leaning rhythm, and both play the bluegrass festival circuit alongside their indie-folk audiences. OCMS has been deeply embedded in the string-band scene from the start; “Wagon Wheel” is now a bluegrass and old-time jam standard. Trampled by Turtles’s high-tempo picking and Dave Simonett’s songwriting put them closer to the working bluegrass community than to the Mumford end of the wave. Neither band claims bluegrass as a primary identity, but both sit on the genre’s edge in a way the arena-pop end of the substyle doesn’t.

The sonic signature, what music journalists and the bands themselves came to call the “stomp-clap” sound: an acoustic-string-band-derived instrumental setup (banjo, mandolin, guitar, sometimes upright bass) augmented with a kick drum, group hand-claps, and big climactic crescendos that worked the same release-and-build dynamic arena rock had been working since the 1970s. The harmonic vocabulary stayed in the mainstream pop-folk zone — major-mode, four-chord progressions, sing-along choruses — and the lyrics were generally first-person-confessional or anthemic-aspirational rather than the third-person narrative of the older bluegrass ballad tradition. The aesthetic borrowed bluegrass instruments and the visual signaling of acoustic-Americana authenticity; it did not borrow the bluegrass solo-sequence convention, the tenor-and-baritone harmony stack, or the bluegrass repertoire.

The distinction from neighbors: where Acoustic Americana (above) is quieter, songwriter-focused, and shares actual players with the bluegrass scene, Stomp clap is louder, arena-aimed, and built on pop-rock arrangement conventions. Where Jamgrass (above) descends from the jam-band tradition (Grateful Dead, Phish) and shares the bluegrass festival circuit with bluegrass acts, Stomp clap descends from indie-rock and never really overlapped with the bluegrass festival circuit. The substyle’s wave crested in roughly 2014 and has since receded; the bands continue to work, with smaller mainstream visibility and an Americana-rather-than-bluegrass identity.

The boundary: where bluegrass overlaps with adjacent music

Bluegrass has neighbors, and the boundaries blur. The instruments — banjo, mandolin, fiddle, guitar, upright bass — turn up in several other American string traditions; the same song can travel from one to another; and players cross between them all the time. The traditions are nonetheless distinct in repertoire, scene, and self-identification.

The confusion almost always runs in one direction. Mainstream listeners — music journalists especially — tend to call things bluegrass that the bluegrass world doesn’t: Mumford & Sons, the Avett Brothers, the Lumineers, Trampled by Turtles, Old Crow Medicine Show. These acts share string-band instrumentation and some harmonic vocabulary with bluegrass, but they don’t generally call their own music bluegrass and the working bluegrass community doesn’t either. We respect those self-identifications. If an artist doesn’t call themselves bluegrass, we don’t insist they are. The full discussion of where this wave came from and what it kept and discarded from bluegrass lives in the Stomp clap section above.

Old-time and Appalachian string band. The closest neighbor — same instruments, much shared repertoire, regular crossover of players. The differences are real but small: old-time emphasizes the dance pulse, bluegrass the rhythm-section drive; old-time banjo is clawhammer, bluegrass banjo is Scruggs-style three-finger; old-time repertoire centers on Appalachian fiddle tunes and pre-WWII ballads, bluegrass repertoire centers on the post-1946 songbook; old-time is jam-and-dance-oriented, bluegrass is concert-and-stage-oriented. The full picture is in our old-time companion essay; the bluegrass acts who live in the overlap zone are in the String band and Mountain ballad sections above.

Country and country-songwriter. Bluegrass shares a common ancestor with pre-WWII country through the Carter Family and Jimmie Rodgers, and players have crossed back and forth ever since. Bluegrass-to-country: Ricky Skaggs, Keith Whitley, Vince Gill, Marty Stuart, Patty Loveless. Country-to-bluegrass: Chris Stapleton (who founded the SteelDrivers in 2005), Sturgill Simpson (whose Cuttin’ Grass, Vol. 1 and 2 in 2020 were full bluegrass projects), Tyler Childers. The songbook crosses the line just as easily: the Hank Williams, Merle Haggard, George Jones, John Prine, Townes Van Zandt, and John Hartford catalogs are in the working bluegrass repertoire and have been for decades. The full discussion is in the Country bluegrass and Country-folk songwriter sections above, and in our country companion essay.

Jug band. A pre-WWII African American urban string-band tradition out of Memphis and Louisville — the Memphis Jug Band, Cannon’s Jug Stompers, Gus Cannon, Will Shade — rooted in country blues and reaching across rags, breakdowns, tin pan alley, minstrel, jazz, ragtime, and hokum, with jug, kazoo, and washboard alongside the strings. The folk revival picked it up through the Jim Kweskin Jug Band (Cambridge, 1960s) and the Even Dozen Jug Band (NYC); the modern lineage runs through Dom Flemons and the Carolina Chocolate Drops. Parallel to old-time and to bluegrass, not derivative of either. The traditions occasionally share a tune; the scenes are distinct.

Western swing. A separate string-and-horns tradition with its own long cast — Bob Wills, Milton Brown, Spade Cooley, the Light Crust Doughboys, and Hank Thompson in the founding generations; Asleep at the Wheel, the Time Jumpers, and Hot Club of Cowtown carrying it forward — built on swing rhythm rather than bluegrass drive. “San Antonio Rose” gets recorded across the line (Ricky Skaggs has cut it) and turns up at the occasional bluegrass jam, but the rhythmic feel, the instrumentation, and the scene are clearly their own thing.

The Picker’s Guide catalog leans inclusive at every one of these boundaries. The working test is whether the song could plausibly be called at a bluegrass jam — and that test catches a lot of material from outside the bluegrass canon that bluegrass musicians have adopted.