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Jefferson County
Sign in to saveAlso known as Jefferson County, Missouri, Jefferson County, MO
county in Missouri, United States
Key facts
- Country
- United States
- State
- Missouri
- Named after
- Thomas Jefferson
- Seat
- Hillsboro
- Largest city
- Arnold
- Total
- 664 sq mi (1,720 km )
- Land
- 657 sq mi (1,700 km )
- Water
- 7.7 sq mi (20 km ) 1.2%
- Estimate 2025
- 233,132
- Density
- 345/sq mi (133/km )
- Time zone
- UTC−6 ( Central )
- Summer dst
- UTC−5 ( CDT )
- Congressional districts
- 3rd , 8th
- Website
- www .jeffcomo .org
via Wikipedia infobox
Wikidata facts
- Named after
- Thomas Jefferson
- Country
- United States
- Located in
- Missouri
- Capital
- Hillsboro
- Population
- 226739
- Area
- 1720
- Shares border with
- St. Louis County
- Official website
- www.jeffcomo.org
- Image
- Jefferson County MO courthouse-20140524-015.jpg
- Households
- 84978
Show 6 more facts
- Commons category
- Jefferson County, Missouri
- topic's main category
- Category:Jefferson County, Missouri
- inception
- 1818-00-00
- water as percent of area
- 1.2
- native label
- Jefferson County
- per capita income
- 30800
Sources (11)
via Wikidata · CC0
~16 min read
Encyclopedic overview
Jefferson County is located in the eastern portion of the U.S. state of Missouri. It is a part of the St. Louis Metropolitan Area. As of the 2020 census, the population was 226,739, making it the sixth-most populous county in Missouri. Its county seat is Hillsboro. The county was organized in 1818 and named in honor of former president Thomas Jefferson. In 1980, according to the U.S. census held that year, the county contained the mean center of U.S. population. Notably, this was the first census in which the center of population was west of the Mississippi River. Jefferson County is part of the St. Louis Metropolitan Statistical Area and encompasses many of the city's southern suburbs.
Geography
Excerpted from Wikipedia’s “Jefferson County” article, available under the CC BY-SA 4.0 licence.