Public holidays
1666, USA, Illinois
| # | Date | Public holiday |
|---|---|---|
| 1 | Friday, January 1, 1666 | New Year's Day |
| 2 | Friday, February 12, 1666 | Lincoln's Birthday |
| 3 | Monday, February 22, 1666 | Washington's Birthday |
| 4 | Sunday, May 30, 1666 | Memorial Day |
| 5 | Sunday, July 4, 1666 | Independence Day |
| Monday, July 5, 1666 | Independence Day (observance) | |
| 6 | Monday, September 6, 1666 | Labor Day |
| 7 | Tuesday, November 2, 1666 | Election Day |
| Friday, December 24, 1666 | Christmas (observance)/Christmas Eve | |
| 8 | Saturday, December 25, 1666 | Christmas |
| Friday, December 31, 1666 | New Year's Day (observance) |