United States · permanent state record · SD
South Dakota
South Dakota at a glance
- Capital
- Pierre · L6 on the national map
- U.S. Census Bureau, Guide to 2010 State and Local Census Geography: South Dakota · Capital field in the Census state geography guide; source page checked 2026-09-13. This is a federal secondary reference, not the designating constitution or statute.
- Admitted to the Union
- 1889-11-02
- U.S. Senate, South Dakota: States in the Senate timeline · Federal institutional history; this is a secondary reference to the act, ratification, or proclamation establishing statehood, not the enrolled act itself.
- Total area
- 77116.1 square miles
- U.S. Census Bureau, State Area Measurements and Internal Point Coordinates · Total area: land and water.
- Population
- 935,094 people
- U.S. Census Bureau, Vintage 2025 Population Estimates · Vintage 2025 resident population estimate.
- ZIP Code range
- 570–577
- U.S. Postal Service, ZIP Code system · Summary of ZIP Code prefixes principally assigned to the state; ZIP Codes are routing constructs, not geographic boundaries.
- Area codes
- 605
- North American Numbering Plan Administrator, NPA reports · In-service geographic area codes assigned to the state.
Selected dated milestones · not a complete state history
South Dakota through time
Admitted to the Union
South Dakota was admitted to the Union on 1889-11-02.
U.S. Senate, South Dakota: States in the Senate timeline · as of 2026-09-04