To most Massachusetts residents—and long distance running enthusiasts—the third Monday in April is “Marathon Monday.” The Boston Marathon has shared the limelight in the Bay State with another celebration for the last 120 years: Patriots’ Day. So what is Patriots’ Day, and what does it have to do with the marathon?

For the answer, let’s travel back to the American Revolution. On April 19, 1775, the Battles of Lexington and Concord kicked off the colonists’ fight for independence from Great Britain. Just two months after Parliament declared Massachusetts to be in a state of rebellion, the brave residents of the colony took up arms and went to battle for independence—eventually leading to the creation of the United States of America.

In 1894, Massachusetts Governor Frederic T. Greenhalge was looking to replace Fast Day (a then-rarely followed day of fasting and prayer that had been around since the 17th century) in the state calendar without causing his constituents to lose a day of work. Greenhalge found inspiration in the state’s courageous battle for freedom from British rule, renaming the holiday Patriots’ Day and moving it to April 19. The new celebration would not only commemorate the battles that officially marked the American Revolution, but also the anniversary of the Baltimore riot of 1861—commonly known as the first bloodshed of the American Civil War. Three birds, one stone.

In 1897, inspired by the revival of the marathon race in the previous year’s summer Olympic games in Athens, the Boston Marathon was added as part of the celebration of Patriots’ Day. It became a much-revered April 19 tradition, almost more so than the original holiday. The Boston Red Sox have even become part of Patriots’ Day, playing a game at Fenway Park at 11:05 a.m., allowing fans to catch the end of the race (a tradition that started in 1959). In 1969, the entire celebration was shifted to the third Monday in April to create a three-day weekend.

The holiday is only officially celebrated in two other states, Maine and Wisconsin (although they still celebrate it on April 19). Residents in Florida are also encouraged to participate, but it has not been designated as an official Sunshine State holiday.