The migration of African Americans to the urban industrial centers of Chicago, Detroit, New York, Los Angeles and elsewhere in the 1930s created a new market for jazz, blues, and related genres of music, often performed by full-time musicians, either working alone or in small groups. The precursors of rhythm and blues came from jazz and blues, which overlapped in the 1930s through the work of musicians such as The Harlem Hamfats, with their 1936 hit "Oh Red", as well as Leroy Carr, Cab Calloway, Count Basie, and T-Bone Walker. There was also increasing emphasis on the electric guitar as a lead instrument, as well as the piano and saxophone.
Late 1940s

In 1949, the term "Rhythm and Blues" replaced the Billboard category Harlem Hit Parade. Also in that year, "The Huckle-Buck", recorded by band leader and saxophonist Paul Williams, was the #1 R&B tune, remaining on top of the charts for nearly the entire year. Written by musician and arranger Andy Gibson, the song was described as a "dirty boogie" because it was risque and raunchy. Paul Williams and His Hucklebuckers' concerts were sweaty riotous affairs that got shut down on more than one occasion. Their lyrics, by Roy Alfred (who later co-wrote the 1955 hit "(The) Rock and Roll Waltz"), were mildly sexually suggestive, and one teenager from Philadelphia said "That Hucklebuck was a very nasty dance". Also in 1949, a new version of a 1920s blues song, "Ain't Nobody's Business" was a #4 hit for Jimmy Witherspoon, and Louis Jordan and the Tympany Five once again made the top 5 with "Saturday Night Fish Fry". Many of these hit records were issued on new independent record labels, such as Savoy (founded 1942), King (founded 1943), Imperial (founded 1945), Specialty (founded 1946), Chess (founded 1947), and Atlantic (founded 1948).
Early to mid 1950s
Johnny Otis, who had signed with the Newark, New Jersey-based Savoy Records, produced many R&B hits in 1951, including: "Double Crossing Blues", "Mistrustin' Blues" and "Cupid's Boogie", all of which hit number one that year. Otis scored ten top ten hits that year. Other hits include: "Gee Baby", "Mambo Boogie" and "All Nite Long". The Clovers, a vocal trio who sang a distinctive sounding combination of blues and gospel, had the #5 hit of the year with "Don't You Know I Love You" on Atlantic Records. Also in July 1951, Cleveland, Ohio DJ Alan Freed started a late-night radio show called "The Moondog Rock Roll House Party" on WJW-AM (850). Freed's show was sponsored by Fred Mintz, whose R&B record store had a primarily African American clientele. Freed began referring to the rhythm and blues music he played as "rock and roll".In 1951, Little Richard Penniman began recording for RCA Records in the jump blues style of late 1940s stars Roy Brown and Billy Wright. However, it wasn't until he prepared a demo in 1954, that caught the attention of Specialty Records, that the world would start to hear his new, uptempo, funky rhythm and blues that would catapult him to fame in 1955 and help define the sound of rock 'n' roll. A rapid succession of rhythm and blues hits followed, beginning with "Tutti Frutti" and "Long Tall Sally", which would influence performers such as James Brown, Elvis Presley, and Otis Redding.
Ruth Brown on the Atlantic label, placed hits in the top 5 every year from 1951 through 1954:
"Teardrops from My Eyes", "Five, Ten, Fifteen Hours", "(Mama) He Treats Your Daughter Mean" and "What a Dream". Faye Adams's "Shake a Hand" made it to #2 in 1952. In 1953, the R&B record-buying public made Willie Mae Thornton's original recording of Leiber and Stoller's "Hound Dog" the #3 hit that year. Ruth Brown was very prominent among female R&B stars. Ruth Brown’s popularity most likely derived because of “her deeply rooted vocal delivery in African American tradition” That same year The Orioles, a doo-wop group, had the #4 hit of the year with "Crying in the Chapel".
Fats Domino made the top 30 of the pop charts in 1952 and 1953, then the top 10 with "Ain't That a Shame".Ray Charles came to national prominence in 1955 with "I Got a Woman". Big Bill Broonzy said of Charles' music: "He's mixing the blues with the spirituals... I know that's wrong."
In 1954 The Chords' "Sh-Boom" became the first hit to cross over from the R&B chart to hit the top 10 early in the year. Late in the year, and into 1955, "Hearts of Stone" by The Charms made the top 20.
At Chess Records in the spring of 1955, Bo Diddley's debut record "Bo Diddley"/"I'm A Man" climbed to #2 on the R&B charts and popularized Bo Diddley's own original rhythm and blues beat that would become a mainstay in rock and roll.
At the urging of Leonard Chess at Chess Records, Chuck Berry had reworked a country fiddle tune with a long history, entitled "Ida Red". The resulting "Maybellene" was not only a #3 hit on the R&B charts in 1955, but also reached into the top 30 on the pop charts. Alan Freed, who had moved to the much larger market of New York City, helped the record become popular with white teenagers. Freed had been given part of the writers' credit by Chess in return for his promotional activities; a common practice at the time.
Late 1950s

Film makers took advantage of the popularity of "rhythm and blues" musicians as "rock n roll" musicians beginning in 1956. Little Richard, Chuck Berry, Fats Domino, Big Joe Turner, The Treniers, The Platters, The Flamingos, all made it onto the big screen.
Two Elvis Presley records made the R&B top five in 1957: "Jailhouse Rock"/"Treat Me Nice" at #1, and "All Shook Up" at #5, an unprecedented acceptance of a non-African American artist into a music category known for being created by blacks. Nat King Cole, a former jazz pianist who had had #1 and #2 hits on the pop charts in the early 1950s ("Mona Lisa" at #2 in 1950 and "Too Young" at #1 in 1951), had a record in the top 5 in the R&B charts in 1958, "Looking Back"/"Do I Like It".
In 1959, two black-owned record labels, one of which would become hugely successful, made their debut: Sam Cooke's Sar, and Berry Gordy's Motown Records. Brook Benton was at the top of the R&B charts in 1959 and 1960 with one #1 and two #2 hits. Benton had a certain warmth in his voice that attracted a wide variety of listeners, and his ballads led to comparisons with performers such as Cole, Sinatra and Tony Bennett. Lloyd Price, who in 1952 had a #1 hit with "Lawdy Miss Clawdy" regained predominance with a version of "Stagger Lee" at #1 and "Personality" at #5 for in 1959.
The white bandleader of the Bill Black Combo, Bill Black, who had helped start Elvis Presley's career, was popular with black listeners. Ninety percent of his record sales were from black people, and his "Smokey, Part 2" (1959) rose to the #1 position on black music charts. He was once told that "a lot of those stations still think you're a black group because the sound feels funky and black." Hi Records did not feature pictures of the Combo on early records.