African Americans developed rhythm and blues in the early 1940s as a hybrid of country blues and big-band swing. In the coming decades R&B evolved in one direction into rock ’n’ roll, and in another direction into soul.

While “race” records sold well in the 1920s (Mamie Smith recorded the first blues record in 1920), their sales plummeted during the Great Depression. The major labels lost interest in black-oriented music, but after the Second World War small, independent labels began to take advantage of the lower cost of recording technology and the untapped market. At the same time, black music began to change as big bands were forced to pare down for lack of work and rural blues artists moved to cities. Possibly the best way to describe R&B in the early era is as a hybrid of the blues with bigband swing—a typical R&B song of the period mixing swinging horn riffs with a rolling boogie rhythm—what Louis Jordan called the Jump Blues. By the 1950s Billboard’s Jerry Wexler had renamed “race” music “rhythm and blues.” In Southern California, artists like Lowell Fulson, T-Bone Walker and Johnny Otis played to packed houses at the Barrel House in the Watts section of Los Angeles, while their music reached larger audiences through local labels like Aladdin, Excelsior and Specialty. In New York, the Erteguns started Atlantic Records, and the Chess brothers opened Aristocrat and then Chess Records (recording the transplanted Delta blues of Muddy Waters and Howlin’ Wolf). New Orleans R&B took its boogie rhythm from the piano, with honking saxes laid over the top. Producer Dave Bartholomew was responsible for many classic early R&B sessions, including those by Fats Domino and Little Richard.

Always a melange, R&B became difficult to distinguish from rock ’n’ roll by the mid-1950s, and in many ways there was no difference—the term “rock ’n’ roll” gaining prevalence only when white performers and audiences took over. Still, while Fats Domino, Little Richard and Chuck Berry may have moved seamlessly into rock ’n’ roll, other important black artists of the 1950s continued in a distinctly R&B vein—Big Mama Thornton, Screamin’ Jay Hawkins and Ike Turner only occasionally crossed over.

R&B also developed into what came to be called soul music in the 1960s with the additional influence of the church. Artists such as Ray Charles, Jackie Wilson and James Brown effected a transformation in black music from R&B to soul when they began to add the emotional expressiveness of gospel music. R&B survives today as a general category of black music, though without any formal accuracy. The influence of R&B, however, can be felt in nearly all popular music forms, from rock ’n’ roll to disco to rap.