In 1948, Mahalia Jackson recorded "Move On Up a Little Higher" for Apollo Records, selling one million copies in the United States. A white radio DJ, Studs Terkel, helped to popularize the recording, playing it alongside the hit rhythm and blues records of the day. With her riveting contralto, Jackson was as captivating as popular blues singers, and gospel's bouncing beat proved just as danceable, even to those who didn't go to church. Jackson began to tour extensively. And though she battled racism and segregation, especially in the South, she could collect hundreds of dollars for a single concert. In 1950, she was invited to perform at Carnegie Hall as the headlining act at the First Negro Gospel Music Festival, a monumental event in the history of gospel music.