Evacuation Day is a holiday observed on March 17 in Suffolk County (which includes the cities of Boston, Chelsea, Revere, and the Town of Winthrop) and also by the public schools in Somerville, Massachusetts. The holiday commemorates the evacuation of British forces from the city of Boston following the Siege of Boston, early in the American Revolutionary War. Schools and government offices (including some Massachusetts state government offices located in Suffolk County) are closed. If March 17 falls on a weekend, schools and government offices are closed on the following Monday in observance. It is the same day as Saint Patrick's Day, a coincidence that played a role in the establishment of the holiday.