In Massachusetts, Marathon Monday is formally known as Patriots’ Day. The holiday is celebrated in Maine, too, but by another name: Patriot’s Day.
The reason Maine went with the singular possessive rather than the plural is unknown, according to The Portland Press Herald, which called for the apostrophe to be moved a character to the right in 2014.
Maine began celebrating Patriot’s Day in 1907, 13 years after Massachusetts began to recognize Patriots’ Day, according to CentralMaine.com. That article says some people support dropping the apostrophe altogether. That’s the approach the upcoming Mark Wahlberg film about the 2013 Boston Marathon bombings is taking. Its official title is “Patriots Day” — no apostrophe — according to sources with the production.
Boston Marathon 2016