Labor Day, Memorial Day, Presidents' Day (we used to celebrate both Washington's and Lincoln's birthdays, but since both are in February, we combined the holiday into one),
Martin Luther King Jr. Day, the Fourth of July, Easter (Sunday),
Christmas,
Columbus day,
Veterans' Day,
Thanksgiving, Halloween,
Mother's Day, Father's Day, Valentine's Day,
New Year's Day, and
St. Patrick's Day are our recognized holidays and are the same all over the country (I might be forgetting a few.) The bolded ones are when both school and the government is closed. Columbus Day and Veterans' Day, the government is closed. The rest are celebrated on the same day but nothing's closed. I forget if we get Mother's and Father's days off, but I think they're always on Sundays anyway so I bolded them too.
Some schools will also give off on various Jewish holidays like Yom Kippur.