In the 1950s, the two record labels that really drove rock and roll into the mainstream were Sun Records (Elvis, Carl Perkins, Jerry Lee Lewis, Johnny Cash) and Chess Records (Chuck Berry, Bo Diddley, Howlin' Wolf, Ike Turner, Larry Williams, Muddy Waters).

When these two labels started turning out the hits, the major labels started signing and releasing rock artists as well. All the labels wanted to sign black rock and rollers like you heard on Chess.

When the 1960s came along, two new labels transformed the trajectory of black rock and roll: Motown/Tamla, and Stax/Volt. Black rock moved away from the 1950s sounds of Chuck Berry, and gradually moved toward the new sounds of the Miracles, the Supremes, the Temptations, Booker T & The MGs, and Otis Redding. Out of this scene, artists on other labels emerged, such as Sly & The Family Stone and Kool & The Gang.

Chess tried to follow this new trend with the Four Tops, but the owners wanted to retire. They sold the company in 1969, and after fulfilling the contracts of their signed artists, the label went out of business in 1975.

Meanwhile, in the late 1960s and early 1970s, the established black artists pushed the Motown and Stax sounds further toward funk and soul. This included many artists that had started out closer to traditional rock and roll: Marvin Gaye, Stevie Wonder, the Isley Brothers, James Brown, Joe Tex, the Ohio Players. The new discoveries were in this same funkier vein: George Clinton, the Jackson Five, Isaac Hayes, Curtis Mayfield, Al Green.

Jimi Hendrix was something of an anomoly because he played more in a traditional rock and roll and blues style than his black contemporaries, following in the footsteps of all of Chess Records' greats: John Lee Hooker, Muddy Waters, Howlin' Wolf, Bo Diddley, and Jimmy Rodgers, while most of his black contemporaries were venturing into Otis Redding and Marvin Gaye territory. This is largely because his fame came on the back of the British Invasion, and not through the black music scene in the U.S. When he replaced Mitch Mitchell and Noel Redding with black American artists, the resulting Band of Gypsies betrayed the fact that Hendrix was a blues player at heart, more at home with B.B. King than with Curtis Mayfield, or, for that matter, Chuck Berry.

Chess, Motown, and Stax all maintained "house bands" that played the backing on most of their solo artists' and vocal groups' recordings. (Bo Diddley was one exception. He always maintained his own band.) This is part of the reason you don't hear as much about black rock bands from that era that played their own instruments. Black rock and roll continued to follow the "vocal group" tradition from the 1940s and 50s throughout the 1960s and right into the 1970s, with the Jackson Five, Temptations, Miracles, and Supremes following in the footsteps of earlier artists like the Coasters, Drifters, Platters, Orioles, and Ink Spots.

This was quite common in white rock and roll in its first decade as well, with groups such as the Tokens, the Lettermen, Jan and Dean, the Four Seasons, and Dion & The Belmonts. Those kinds of groups were on their way out when group-oriented surf rock became popular in 1963-64, and then the arrival of the British Invasion pretty much killed it when all the labels stopped signing them in hopes of finding the next Beatles. (A few still managed to break through in the later 1960s, such as the Mamas & The Papas and the Righteous Brothers.)

The short version is that there were black rock and roll groups, but few got on record because many of the major black labels had house bands. Those labels tended to sign vocal groups they thought would be marketable instead of bands that played their own instruments. Black and white rock and roll only ever merged for a little while (though remaining almost 100% segregated) from about 1955 to 1962, and even then white rock was much more country-influenced than its blues-influenced black counterpart.

By 1963, black rock was veering off into Motown and Stax territory, which then became funk and soul and whatever it is that Stevie Wonder plays in the late 60s and early 70s. White rock and roll followed the British Invasion instead, which was followed up with prog rock, folk rock, heavy metal, and all sorts of 70s sounds.