The Golden Gate Jubilee Quartet was founded in 1934 by four students at Booker T. Washington High School in Norfolk, VA. With obvious changes in personnel, and having dropped "Jubilee" at some point, the group is still performing today. They were extremely popular in the '40s and '50s, with many crossover performances. I first became aware of the group because they backed Leadbelly's only recording of "Midnight Special," which was evidently some producer's idea of a good match. That clip is at the bottom of the post, so you can decide for yourselves if it works (I don't think it does, despite the high talent levels).
Audio only:
The most recent clips I found:
Backing Leadbelly in 1934 (audio):
What a treat. Hopeful gospel music on a peaceful Sabbath morning. Thanks.