What African American man was the most recent Democratic mayor of New York City before Bill de Blasio?
Bill de Blasio:  De Blasio is the first Democratic mayor of the city since David Dinkins, from 1990 to 1993. David Dinkins: David Norman Dinkins (born July 10, 1927) is an American politician, lawyer, and author who served as the 106th Mayor of New York City, from 1990 to 1993. David Dinkins:  He was the first and to date, the only African American to hold that office.
David Norman Dinkins