Public holidays
1640, USA, South Dakota
| # | Date | Public holiday |
|---|---|---|
| 1 | Sunday, January 1, 1640 | New Year's Day |
| Monday, January 2, 1640 | New Year's Day (observance) | |
| 2 | Monday, January 16, 1640 | Martin Luther King Day |
| 3 | Monday, February 20, 1640 | Washington's Birthday |
| 4 | Monday, May 28, 1640 | Memorial Day |
| 5 | Wednesday, July 4, 1640 | Independence Day |
| 6 | Monday, September 3, 1640 | Labor Day |
| 7 | Sunday, November 11, 1640 | Veterans Day |
| Monday, November 12, 1640 | Veterans Day (observance) | |
| 8 | Thursday, November 22, 1640 | Thanksgiving |
| 9 | Tuesday, December 25, 1640 | Christmas |