Warner Williams, a Piedmont blues guitar master whose seemingly limitless repertoire spanned country music and pop standards, died Sept. 19 at a nursing home in Gaithersburg, Maryland. He was 91.

The cause was lung cancer, said his son Curtis Williams.

Nattily attired with a cowboy hat and wraparound shades, Williams was a ubiquitous presence throughout suburban Maryland. He performed not only in pubs but busked outside of subway stations and retail stores. Few passersby knew that he also toured the country, taking his music to blues and folk festivals.

Folklorists regarded Williams as one of the last “songsters,” a term reserved for traveling Black troubadours such as Lead Belly and Mississippi John Hurt who performed a wide range of music – not just blues – from traditional sources.

He specialized in Piedmont blues guitar, a fingerpicking style in which a syncopated melody on the high strings is supported by a two-note pattern on the bass strings. The most famous practitioners of the style include Brownie McGhee, John Jackson and John Cephas, although its echoes can also be heard in such country guitarists as Merle Travis.

In the liner notes for Williams’s 2004 album “Blues Highway” (featuring harmonica player Jay Summerour), folklorist Nick Spitzer wrote that the guitarist “brings consummate playing to his eclectic repertoire, complete with unexpected jazz chords, jaunty single-string work, ragtime strums, and basic Piedmont fingerpicking – all complementing his warm, gravelly voice.”

Williams’s repertoire encompassed such Southern blues as “Ain’t Gonna Pick No More Cotton,” “Step It Up and Go,” “Key to the Highway” and an often requested novelty tune, “Hey Bartender, There’s a Big Bug in My Beer.”

However, he also did standards such as “Blueberry Hill” and “Pennies From Heaven” and could perform an entire night of honky tonk songs by Hank Williams and Ernest Tubb. The country songs were a legacy of his youth in Takoma Park, Md., a community then surrounded by farmland.

Though he recalled being jumped in the street by White hooligans, he also had white neighbors who taught him country music and brought him along to perform in taverns even though he was Black – segregation was the norm – and a minor. Williams loved country and recognized a hardscrabble commonality in the lyrics.

“They both got meaning,” he told The WashingtonPost in 2011. “Country ain’t nothing but the blues.”

The young guitarist also performed on Washington street corners while his mother shopped. “She’d come out, I’d have people all around me,” he told Spitzer.

“We’d stand on the corner anywhere,” he added. “We wouldn’t sit down, we’d stand up playing, people would come by, give you some change. The police would run you off one corner, you’d go to the next one. ‘Can’t stand still,’ just like the song says, ‘you got to step it up and go.’ ”

In concert, Williams worked with Summerour and later, drummer Eric Selby and pianist Daryl Davis under the billing Little Bit a Blues. Summerour and Williams met in the early 1980s and put out their first recording, a cassette tape financed by Bill Danoff of the Starland Vocal Band. Four albums followed over the next two decades.

“He never could hold onto a guitar,” producer Tom Mindte recalled. “I never knew what became of the guitars. I know one was stolen from his car. He would play whatever guitar he could get his hands on. Sometimes it was a flap top [acoustic] with a pickup, sometimes it was an electric. But it didn’t matter because he always got great tone. He never had an expensive guitar – but he didn’t need one!”

Mindte recalled that Williams would quickly go from one song to the next, often making him nervous as he watched Summerour scramble to find the right harmonica for each tune.

When the pair took to the road for festival appearances, Summerour contended with Williams’s fear of airplanes. The matter came to a head after a show in Washington state.

“We went out there on the train,” recalled Summerour. “I said Warner, they’ll be back home in five hours, it takes us five days. Coming back, there was a derailment and they had to take us part of the way from Chicago on buses. I didn’t like that too much and I think it got to him, too.”

For their return trip the following year, Davis persuaded him to fly and marveled as he chose – and remained – in a window seat, eyeing the sights below him with fascination. However, when they deplaned, Davis discovered another problem. Williams had never been on an escalator.

Warner George Williams was born in Takoma Park on May 7, 1930. His father was a cement finisher who played fiddle, piano and guitar and pushed all 11 of his kids to sing or play instruments. Warner started playing guitar and piano by age 5.

During the ’50s and ’60s, Williams played electric guitar in rhythm-and-blues bands but mostly supported himself through manual labor. He later drove a garbage truck.

His wife of 45 years, the former Karolyn Reddix, died in 1995. Three of his children died, Warner Williams Jr. in 1991, Estelle Williams in 2000 and Michael Williams in 2010.

Survivors include five children, Alan Jeffrey Williams, Curtis Williams and Sheila Williams, all of Germantown, Md., Steven Williams of Gaithersburg, Md., and Kevin Williams of Point of Rocks, Md.; a sister; nine grandchildren; 19 great-grandchildren; and three great-great-grandchildren.

In 2011, Williams received a National Heritage Fellowship from the National Endowment for the Arts, the nation’s highest honor for a traditional musician. Davis said Williams received an $25,000 honorarium, some of which paid for a new van.

When not performing, Williams could be found playing keno, accompanying the choir during Sunday service at Oak Grove AME Zion Church in Gaithersburg or working on one of the many old cars parked outside his mobile home in Mount Zion, Maryland. All were adorned in big paste-on letters with the phrase “Guitar Man.”