September 17th (1878) was a Tuesday. It's the 259th day of the year (260th in leap years) in the Gregorian calendar. There are 106 days left to the end of the year.
» Constitution Day (United States) named Constitution Day (observed on the previous Friday if it falls Saturday, the following Monday if on a Sunday), Citizenship Day, Von Steuben Day. (United States)
» Operation Market Garden is still remembered with parachuting and dedications on this day. (Netherlands)