Monday is a holiday...sort of if you live in Boston, Chelsea, Revere, Winthrop, Cambridge or Somerville. Most state offices are open UNLESS they are in Suffolk County and then they are closed...maybe
For example the Registry of Motor Vehicles website says the Roslindale office is closed but doesn't say if Chinatown is open or closed. Best advice call ahead if you have official business today in any of those cities or towns.
The holiday, celebrated each March 17 commemorates the day in 1776 when the British redcoats ended their occupation of Boston. By some happy coincidence, March 17 happens to be Saint Patrick's Day. How fortuitous that Suffolk County, a region which has a large percentage of citizens of Irish descent, was able to find an event which just happened to coincide with the day of celebration of Irish culture.
Now you know