The film features interviews with Ira Tucker Jr., whose father was a key member of the legendary Dixie Hummingbirds. He said his father, raised in South Carolina, came north because Philadelphia was known as a city with radio stations that would broadcast gospel music.
That led to a busy schedule of regional appearances and headlining work at the Metropolitan Opera House at Broad and Poplar streets, an institution that would become a magnet for gospel talent - many of whom, like the Hummingbirds, Sister Rosetta Tharpe and Edna Gallmon Cooke decided to make their homes in Philadelphia.
"Back then, there weren't that many places you could go to hear the music other than church. With the Met, now you could go see it in a different setting, designed for music, and see one group after another. That's how it all came together," Tucker said.
Tucker said many artists found a commercial outlet for their work via Gotham records, which during its glory years operated near 16th and Race.
According to legend, Margaret Allison (who founded the Angelic Gospel Singers) walked in off the street in 1949 to record "Touch Me Lord Jesus," a gospel hit that made her a star and put Gotham (along with the Met) on the map as destination for gospel top talent - Sam Cooke of the Soul Stirrers, Lou Rawls of the Pilgrim Travellers.
Philadelphian Ruth Davis - convinced, so the story goes, that God had saved her from a trolley accident - persuaded her sisters to form a female group (the Davis Sisters) to rival the Hummingbirds in talent and technique. They were gospel's most popular female group, perhaps rivaled in fame by Philadelphia's Ward Singers, which was managed with an iron will by mother Gertrude, not always to the liking of her talented daughters (Willa Ward is featured in the documentary).
The groups often shared and exchanged talent - Ward singer Marion Williams left to found the Stars of Faith. Barney Parks of the Dixie Hummingbirds joined Julius Cheeks to form the Sensational Nightingales, another group with deep Philadelphia ties.
Philadelphia native Rev. Isaac Douglas worked as a second lead for the Davis Sisters before forming the Isaac Douglas Singers and the New York Community Choir, recording with Nikki Giovanni, and hitting the charts in 1977 with "Express Yourself."
Through the years, Carpenter noted, the tradition has been kept alive by groups like the Gabriel Hardeman Delegation - like many gospel acts, equally at home writing gospel songs ("Feels Like Fire") or R&B hits for Stephanie Mills and Miki Howard.
Carpenter added that "while not gospel per se," Philadelphia artists with links to the gospel tradition include Marian Anderson, Solomon Burke and Ethel Waters, who made "His Eye Is on the Sparrow" a popular fixture on the Billy Graham Crusades.