Missouri·MO·FIPS 29099

Jefferson County

Voted Republican in 2024 · 119,314 votes cast

About Jefferson County

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.

2024 Presidential Results

All candidates · Jefferson County, Missouri

Donald J Trump(Republican)

67.7%80,796

Won by 43,831 votes

Kamala D Harris(Democrat)

31.0%36,965

Chase Oliver(Libertarian)

0.8%947

Other(Other)

0.5%606

Margin History

Red = Republican, Blue = Democratic

2024R+36.7

2020R+33.9

2016R+35.3

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Swung Right in 2024

Jefferson County shifted 2.9 points toward Republicans compared to 2020. Voter turnout increased by 2.3%.

Jefferson County — Local Discussion

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What does Jefferson County really think?

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Election data: MIT Election Data Science Lab, Harvard Dataverse (CC BY 4.0)