Hailed the "Queen of Gospel," Walker began singing in the choir of West Point Baptist Church in Chicago at the age of 4. In 1951, at age 22, she founded the Caravans, which helped launch the music careers of gospel legends such as Shirley Caesar, Inez Andrews, Dorothy Norwood, Bessie Griffin and the Rev. James Cleveland.

Known for such hit songs as "I Won't Be Back," "Mary Don't You Weep," "I'm Not Tired Yet," "Sweeping Through the City" and "No Coward Soldier," the group achieved wide fame in the late 1950s--headlining at Carnegie Hall and other high-profile venues.

"Though we have lost an American icon, her influence on gospel music will continue for generations," President Barack Obama said. "Our thoughts and prayers are with her family and the countless lives she touched."

Walker went solo in 1975, and in 1994 won a GRAMMY for Best Traditional Soul Gospel Album for her project Songs of the Church (Verity Records).

Walker was inducted into the Gospel Music Hall of Fame in 2001. The following year President George W. Bush honored Walker for her contribution to gospel music in a ceremony at the White House during which he also declared June as Black Music Month.

Her last major performance was in June with a reunited version of the Caravans at the Chicago Gospel Music Festival, the Chicago Tribune reported.