Reader Wayne sent us some great information about this location, and we thank him.
"This terminal was built in 1925 by Detroit United Ryls. People transferred from the interurban cars to buses for the trip downtown in an effort to speed up the service. The big interurban cars spent too much time caught in auto traffic. Passengers did not want to transfer and downtown service by rail cars resumed in 1927. I think the terminal closed at that time or was used by the city for records storage until it was sold to a church in the early 1950's."
Peter Dudley sent us the following details as well - thanks Peter.
Gary Transfer Terminal opened 3-19-1925 as the southern terminus of Detroit United Railway's Rapid Railway interurban line, which once extended as far north as Port Huron. DUR intended that its rail passengers continue to Downtown Detroit on its own buses. The DUR cars avoided trackage further south, which had been taken over by Detroit's Department of Street Railways (DSR) in 1922. DUR would have had to pay DSR to use the tracks DUR had built years earlier. Sometime c. 1926-1928, DSR leased the building, re-named it Gary Garage, and stored buses here. DUR went bankrupt in 1928. DSR streetcars NEVER used this facility. DSR's lease expired 11-14-1930. I have no firm info about any use after that date. This might be the longest-abandoned building still standing in Detroit (1930-2011); 80 years and counting.