These are the official 10 holidays. Some dates are changed slightly in order to give people a 3-day weekend by making the nearest Monday the holiday.
These are Federal holidays. All govt offices are closed, there is no mail delivery and banks are closed. There may be a couple more specific to the state you live in but only celebrated by the people living in that state.
2018 Federal Holidays
Monday January 1
New Year’s Day
Monday January 15
Birthday of Martin Luther King, Jr.
Monday February 19 Washington’s Birthday
Monday May 28
Wednesday July 4
Monday. September 3
Monday. October 8
Monday November 12
Thursday November 22 Thanksgiving Day
Tuesday December 25