Wanda Whitney writes: “This week marks the 100th anniversary of the Tulsa Race Massacre, in which a mob of whites invaded and burned to ashes the thriving African American district of Greenwood, also known as Black Wall Street. I had heard about the Greenwood massacre before but didn’t know much about its history. Then late last year, a patron contacted our Ask a Librarian service with a question about racial massacres. That spurred me to investigate the library’s collections to see what I could find out about the Tulsa massacre and similar events that occurred in the United States in the post-World War I era.”