Public holidays
1644, USA, South Dakota
| # | Date | Public holiday |
|---|---|---|
| 1 | Friday, January 1, 1644 | New Year's Day |
| 2 | Monday, January 18, 1644 | Martin Luther King Day |
| 3 | Monday, February 15, 1644 | Washington's Birthday/Susan B. Anthony Day |
| 4 | Monday, May 30, 1644 | Memorial Day |
| 5 | Monday, July 4, 1644 | Independence Day |
| 6 | Monday, September 5, 1644 | Labor Day |
| 7 | Friday, November 11, 1644 | Veterans Day |
| 8 | Thursday, November 24, 1644 | Thanksgiving |
| 9 | Sunday, December 25, 1644 | Christmas |
| Monday, December 26, 1644 | Christmas (observance) |