I guess it was a little more than a year after Hoover LEFT office. An interesting little factoid is that Hoover actually carried Pennsylvania, mainly due to the Pittsburgh area, in his unsuccessful re-election bid in 1932, along with five other states, all in the northeast.
The last Republican Mayor here apparently left office with the cloud of some type of scandal hanging over him. I’m not familiar with the details. The area became a real hotbed of labor union activism about that time and they went all-in with the Dems. There was a Catholic Priest named Father Cox who was leading the charge. Held big rallies and did radio shows. That tying of unions and Democrats and the Church together at the wrists and ankles is why Dem voting patterns here are so ingrained to this day.