In the late 1950s and 1960s, Mahalia Jackson was not only renowned as a gospel singer; she achieved a surprising (from our vantage point) mainstream fame. She was "the main attraction in the first gospel music showcase at the Newport Jazz Festival in 1957," and at the 1963 March on Washington, site of MLK's "I Have a Dream" speech, "she sang in front of 250,000 people", according to Wikipedia. At John F. Kennedy's Inaugural Gala in 1961, produced by Frank Sinatra, Jackson performed along with Harry Belafonte, Nat King Cole, Ella Fitzgerald, Gene Kelly, Janet Leigh, Ethel Merman, Sidney Poitier, and Anthony Quinn, all top celebrities of the day.
But maybe the best evidence of her celebrity comes from her appearance as a "mystery guest" on the popular TV quiz show What's My Line? (see below for more about the show), which she made soon after she performed at JFK's Inaugural. It's charming 6-minute clip, though I do wish we'd heard more from her....
What's My Line was a long running (1950-1967) CBS game show, in which a panel of minor celebrities du jour attempted to guess a contestant's occupation by asking a series of YES/NO questions. In the final round of each episode, the panel members donned blindfolds and attempted to guess the identity of a celebrity "mystery guest", as in the clip above.
As a little lagniappe, here's Louis Armstrong on What's My Line?