Paid days off were first introduced in the US in 1885. Initially, only employees of state institutions and offices were entitled to them. Over time, the holiday list was extended to 10, and the right to paid time off was also extended to the private sector.
Here is a complete list of United States holidays:
The list includes 10 non-working days, and each state may introduce additional holidays.
Rules have been introduced which make it possible to celebrate regardless of what day the day off is. If a holiday falls on a Saturday, it is celebrated on Friday before. If on Sunday - it is moved to Monday.
Using this days calculator you can quickly calculate how many days are left until the next holiday (eg Christmas).