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Standard American Almanac

United States · permanent state record · MO

Flag of Missouri

Missouri

Missouri at a glance

Capital
Jefferson City · M7 on the national map
U.S. Census Bureau, Guide to 2010 State and Local Census Geography: Missouri · 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
1821-08-10
U.S. Senate, Missouri: 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
69706.9 square miles
U.S. Census Bureau, State Area Measurements and Internal Point Coordinates · Total area: land and water.
Population
6,270,541 people
U.S. Census Bureau, Vintage 2025 Population Estimates · Vintage 2025 resident population estimate.
ZIP Code range
630–658
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
235, 314, 417, 557, 573, 636, 660, 816, 975
North American Numbering Plan Administrator, NPA reports · In-service geographic area codes assigned to the state.

Selected dated milestones · not a complete state history

Missouri through time

  1. Admitted to the Union

    Missouri was admitted to the Union on 1821-08-10.

    U.S. Senate, Missouri: States in the Senate timeline · as of 2026-09-04