The ANSWERS are in!
This is a Hodiamont streetcar going westbound on Olive at Compton. The top of the Gateway Arch in the background is a clue that the photo was taken in the mid-1960s after the Arch was topped out in 1965, but before the Hodiamont line’s final run in 1966.
Today, Circus Flora is in town and the big top is up near this photo’s location in Grand Center. Ride MetroBus to their new show, “The Case of the Missing Bellhop” this weekend. https://circusflora.org/