These songs are the "roots" of rock & roll music.

Rock and roll (often written as rock & roll or rock 'n' roll) is a genre of popular music that originated and evolved in the United States during the late 1940s and early 1950s, primarily from a combination of African-American genres such as blues, boogie woogie, jump blues, jazz, and gospel music, together with Western swing and country music. Though elements of rock and roll can be heard in blues records from the 1920s and in country records of the 1930s, the genre did not acquire its name until the 1950s.