Between 1619 and 1865, many blacks were brought to the United States and enslaved. While working in the fields or in the houses, slaves used to sing their emotions, their state of mind, their soul. This kind of song is called "worksongs".
Then, the jazz, who appeared after the First World War, used to be the preferred mode of expression of the Afro American singers and musicians. The jazz were appeared and were really developped in the New Orleans a city of Louisiana.
The Rock 'n' Roll were borned around 1950 in the United States. Appeared in the form of rock 'n' roll, it then resembles a mixture of jazz, blues, country, etc...Elvis Presley, famous white rocker is often quote but we must not forget Chuck Berry, famous black rocker !