Patriot's Day AKA Patriots' Day

• It is an American civic holiday commemorating the anniversary of the Battles of Lexington and Concord on April 19, 1775 which were the first battles in American Revolution.
• It is officially Patriots' Day in Massachusetts and Wisconsin and Patriot's Day in Maine.
• It was previously celebrated every April 19 but in 1969, it was moved and has been observed every third Monday of April.
• It was first proclaimed by Gov. Frederic T. Greenhalge in Massachusetts in 1894 as a replacement for the public holiday of Fast Day.
• It was established on April 19 to consolidate the longstanding municipal observances of Lexington Day and Concord Day and also marked the first bloodshed of the American Civil War in the Baltimore riot of 1861 wherein  four Massachusetts militia members were slain and 36 injured and these dual commemoration celebrated "the anniversary of the birth of liberty and union" according to Gov. Greenhalge.
• Massachusetts legislature passed a bill in 1938 establishing the holiday "in commemoration of the opening events of the War of the Revolution."
• Following the proclamation in 1894, Maine followed Massachusetts in 1907 and replaced its Fast Day with Patriot's Day.
• Observances and re-enactments of these first battles of the American Revolution occur annually at Lexington Green in Lexington, Massachusetts, (around 6:00 am) and The Old North Bridge in Concord, Massachusetts, (around 9:00 am).
• State police escorts those who retrace the rides of Paul Revere and William Dawes calling out warnings the whole way. Paul Revere is an American silversmith who is known for spreading the word of the Boston Tea Party to New York and Philadelphia and for warning the Lexington Minutemen about the British invasion in 1775. The story of his “midnight” ride to Lexington to discuss action plans against the British has been immortalized in a poem by Henry Wadsworth Longfellow entitled "Paul Revere's Ride".
• There are re-enactments of the events leading to the battles of 1775 and a major highlight is the bell ringing which was the warning for the local troops that British soldiers were approaching.
• The Boston Marathon, technically the world's oldest continuously running marathon, is a major event held during Patriots' Day and is also referred as "Marathon Monday" by many Bostonians.
• The Boston Red Sox have been playing every year since 1959 in Fenway Park on Patriots' Day and the only games that were postponed due to weather were in 1959, 1961, 1965, 1967, and 1984, and a game cancellation in 1995 due to a late start to the season. Since 1968 the games have started early at around 11:00 am. and this early game start usually resulted in the game ending just as the Boston Marathon is heading through Kenmore Square. Since 2007 the Boston marathon has started between 9:30 am and 10:00 am which resulted to racers going through Kenmore towards the middle of the Red Sox game.

Minute Man Statue by Daderot

References:

In The Neighborhood
Time and Date
Cute-Calendar
National Park Service
Patriots' Day
Academy of American PoetsBartleby
Paul Revere's Ride
About.Com New England Travel
Boston Marathon