On July 20, 1942, Aaron "T-Bone" Walker walked into Capitol Records in Hollywood and recorded "Mean Old World" with pianist Freddie Slack, bassist Jud DeNaut, and drummer Dave Coleman. The record, along with its B-side "I Got a Break, Baby," has since been described as "the first important blues recordings on the electric guitar." Walker was thirty-two years old, already more than a decade into his professional career, and he played the session like a man who had been waiting a long time for someone to turn on a microphone. What came out of that room in 1942 was the sound that every electric blues guitarist since has been measuring themselves against, whether they know it or not.

The reason Walker matters, and the reason he belongs at the center of any serious conversation about the blues canon, is that he solved a problem nobody had formally named yet. Before Walker, the electric guitar in a band setting was a rhythm instrument. It chunked along behind the horns, filling out the bottom of the arrangement. The soloists were the saxophone players, the trumpet players, the men who stepped to the front of the bandstand and wailed. Walker looked at that setup and decided the guitar could do what the horn did. He put it out front. He made it sing single-string lines with the phrasing and the breath of a horn player, and he backed those lines with the harmonic sophistication of the jazz world he had grown up inside. The result was something genuinely new: a guitar voice that could carry a band.

Walker was born in Linden, Texas, on May 28, 1910, and grew up in Dallas in a household where music was constant. His mother played guitar. His stepfather, Marco Washington, played bass in the Dallas String Band. As a teenager, Walker led Blind Lemon Jefferson through the streets of Dallas, which is not a bad education in the blues. He settled in California in 1934 and worked the Central Avenue club circuit, spending time with Les Hite's orchestra in 1939 and 1940, experimenting with a hollowbody archtop and refining a style that owed as much to Count Basie and Duke Ellington as it did to the Delta. His songs featured ninth and thirteenth chords, horn sections, and a laid-back swinging rhythm that was a long way from the raw country blues of the Mississippi. He was combining two worlds deliberately, and by the time he walked into Capitol in 1942, the combination was complete.

After the wartime recording ban lifted, Walker signed with Black and White Records in Los Angeles in 1946, with producer Ralph Bass running the sessions. On September 13, 1947, in Hollywood, he recorded "Call It Stormy Monday (But Tuesday Is Just as Bad)" with a five-piece backing band: Teddy Buckner on trumpet, Bumps Myers on tenor saxophone, Lloyd Glenn on piano, Arthur Edwards on bass, and Oscar Lee Bradley on drums. Released in November 1947, the record reached number five on the R&B charts in 1948 and has since been inducted into both the Blues Hall of Fame and the Grammy Hall of Fame. The full title matters, by the way. Walker named it carefully to distinguish it from Earl Hines and Billy Eckstine's 1942 recording "Stormy Monday Blues," but the confusion cost him royalties for decades when artists covered it under the shortened name.

The session personnel on "Stormy Monday" tells you everything about what Walker was doing. Buckner's trumpet sits in the arrangement the way a second voice would, and the interplay between Walker's guitar and that horn is the whole point. He had taken the call-and-response structure that runs through gospel and the Delta blues and rebuilt it for a small jazz combo with an electric guitar at the center. The twelve-bar form is all there, scripture intact, but the language Walker is speaking over it comes from swing, from the sophisticated harmonic world of Central Avenue. That is the bridge. That is the door he opened.

B.B. King said it plainly: hearing Walker on record was the reason he went out and got an electric guitar. The Allman Brothers Band played "Stormy Monday" at the Fillmore East in 1971 and introduced it to a whole new generation of listeners who may have had no other blues song in their repertoire. Stevie Ray Vaughan and Eric Clapton both traced their vocabulary back to him. Walker's 1950-54 run on Imperial produced further classics including "Cold Cold Feeling" and "Party Girl," and his Atlantic sessions, which ran from a 1955 Chicago date with harmonica player Junior Wells and guitarist Jimmy Rogers through two more Los Angeles sessions in 1956 and 1957, captured a collision of West Coast and Chicago blues that would have been unthinkable without Walker having already built the common language both scenes were speaking.

The licks Walker invented in the 1940s are still in every amplified blues guitar solo being played tonight, in every bar, on every stage. The players throwing them down may not know who wrote them. That is the nature of a foundation: you stop seeing it once the building goes up. But the building is Walker's, and "Mean Old World" and "Stormy Monday" are the blueprints. The jazz world gave him the chords. The blues gave him the feeling. He put them together in a Hollywood studio with a hollowbody archtop and a small combo, and everything that came after had somewhere to stand.