Evacuation Day ( Massachusetts ) March 17 is Evacuation Day , a holiday observed in Suffolk County ( which includes the city of Boston ) and also by the public schools in Cambridge and 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 . Historical background . The 11 - month siege of Boston ended when the Continental Army , under the command of George Washington , fortified Dorchester Heights in early March 1776 with cannon s captured at Ticonderoga . British General William Howe , whose garrison and navy were threatened by these positions , was forced to decide between attack and retreat . To prevent what could have been a repeat of the Battle of Bunker Hill , Howe decided to retreat , withdrawing from Boston to Nova Scotia on March 17 , 1776 . The British evacuation was Washington ' s first victory of the war . It was also a huge morale boost for the Thirteen Colonies , as the city where the rebellion began was the first to be liberated . Establishment of the holiday . While Saint Patrick ' s Day parades have been held in Boston since 1876 , Evacuation Day was not declared a holiday in the city until 1901 , amid interest in local history that also resulted in the construction of the Dorchester Heights Monument . The state made it a holiday in Suffolk County in 1938 . The large Irish population of Boston at that time played a role in the establishment of the holiday . A 1941 law establishing the holiday in Suffolk County was signed in both black and green ink . Observance activities . Evacuation Day activities in the areas that observe the holiday are limited . Most events of note , like the annual parade and politicians ' breakfast in South Boston , are dominated by celebrations of Irish culture . The parade is officially designated the Saint Patrick ' s Day and Evacuation Day Parade . The Allied War Veterans of South Boston mark the day with a ceremony on Dorchester Heights . Another local holiday observing an event in the American Revolutionary War is Bunker Hill Day . State workers outside Suffolk County are allowed to choose any two days off in lieu of celebrating Evacuation Day and Bunker Hill Day on the observance days . The two holidays are generally not observed by the general public or private businesses . Some government services remain in operation , such as trash pickup in the City of Boston and all state Registry of Motor Vehicle offices . The MBTA runs a normal schedule but , due to special events , prohibits bicycles on the subway . Moves to eliminate holiday . In 2010 , the state legislature debated eliminating Evacuation Day and Bunker Hill Day as official holidays , citing the expense of giving state and local workers paid days off . The state ' s FY2011 budget requires all state and municipal offices in Suffolk County be open on both days .