Evacuation Day is a holiday observed on March 17 in Suffolk County, Massachusetts 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 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.

Boston, officially the City of Boston, is the capital and most populous city in the Commonwealth of Massachusetts in the United States. The city serves as the cultural and financial center of the New England region of the Northeastern United States. It has an area of 48.4 sq mi (125 km2) and a population of 675,647 as of the 2020 census, making it the third-largest city in the Northeast after New York City and Philadelphia. The Greater Boston metropolitan statistical area, including and surrounding the city, is the largest in New England and eleventh-largest in the country.