When did the Tulsa Race Riot occur?

The incident began on 31 May 1921, and continued into the next day, 1 June 1921.

Source: Death in a Promised Land (TCCL call# 976.686 E47d 1982), pp.47-57. 

What was the address of the Drexel Building in 1920?

According to the 1920 Tulsa City Directory, the address of the Drexel Building was 319 S. Main. This building is significant in Tulsa's history because according to the Tulsa Daily World, Wednesday, 6/1/1921, it was this building where Dick Rowland, a negro bootblack, was arrested for assaulting a white girl in an elevator. The Tulsa Race Riots broke out soon afterward.

Source: 1920 Tulsa City Directory