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St. Louis County
Sign in to saveAlso known as St Louis County, Missouri, Saint Louis County, St. Louis County, Missouri, St Louis County, Saint Louis County, Missouri, St. Louis County, MO
county in Missouri, United States
Key facts
- Country
- United States
- State
- Missouri
- Founded
- October 1, 1812
- Seat
- Clayton
- Largest city
- Florissant
- County executive
- Sam Page ( D )
- Total
- 523.366 sq mi (1,355.51 km )
- Land
- 507.995 sq mi (1,315.70 km )
- Water
- 15.371 sq mi (39.81 km ) 2.9%
- Estimate 2025
- 990,911
- Density
- 1,943.527/sq mi (750.400/km )
- Time zone
- UTC−6 ( Central )
- Summer dst
- UTC−5 ( CDT )
- Congressional districts
- 1st , 2nd
- Website
- stlouiscountymo.gov
via Wikipedia infobox
~40 min read
Encyclopedic overview
St. Louis County is located in eastern Missouri. It is bounded by the City of St. Louis and the Mississippi River to the east, the Missouri River to the north, and the Meramec River to the south. As of the 2020 census, the population was 1,004,125, making it the most populous county in Missouri, and was estimated to be 987,059 in 2023. Its county seat is Clayton, while the largest city is Florissant. The county is included in the St. Louis, MO–IL metropolitan statistical area.
After Great Britain took over former French territory east of the Mississippi River, many ethnic French colonists moved west. They settled the area of St. Louis County and founded the city of St. Louis in the late 1700s. The US acquired this territory in 1803 with the Louisiana Purchase.
Excerpted from Wikipedia’s “St. Louis County” article, available under the CC BY-SA 4.0 licence.
Gallery (8)
On the map
2 mapped locations