Chicago’s last Republican chief was William Hale “Big Bill” Thompson, who served from 1915 to 1923, then from 1927 to 1931. Thompson was defeated in 1923 by a Democrat, William Dever, who shut down thousands of speakeasies across the city. In return, after Thompson was reelected, the mayor didn’t interfere with the gangster’s operations. Overall, though, a 1993 survey of historians ranked Thompson the worst big-city mayor in American history. No wonder we haven’t had another Republican since.