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 According to the U.S. Census Bureau, the county has a total area of , of which is land and (1.2%) is water. The county's eastern border is the Mississippi River.

Adjacent counties St. Louis County (north) Monroe County, Illinois (east) Ste. Genevieve County (southeast) St. Francois County (south) Washington County (southwest) Franklin County (west)

Major highways

National protected area Middle Mississippi River National Wildlife Refuge (part)

Demographics

2020 census

As of the 2020 census, the county had a population of 226,739 and a median age of 40.3 years. 23.1% of residents were under the age of 18 and 16.2% of residents were 65 years of age or older. For every 100 females there were 99.1 males, and for every 100 females age 18 and over there were 97.1 males age 18 and over.

The racial makeup of the county was 90.4% White, 1.0% Black or African American, 0.3% American Indian and Alaska Native, 0.8% Asian, 0.0% Native Hawaiian and Pacific Islander, 0.8% from some other race, and 6.6% from two or more races. Hispanic or Latino residents of any race comprised 2.4% of the population.

65.2% of residents lived in urban areas, while 34.8% lived in rural areas.

There were 86,959 households in the county, of which 32.4% had children under the age of 18 living with them and 21.7% had a female householder with no spouse or partner present. About 22.9% of all households were made up of individuals and 9.7% had someone living alone who was 65 years of age or older.

There were 92,385 housing units, of which 5.9% were vacant. Among occupied housing units, 80.5% were owner-occupied and 19.5% were renter-occupied. The homeowner vacancy rate was 1.3% and the rental vacancy rate was 7.9%.

Racial and ethnic composition +Jefferson County, Missouri – Racial and ethnic compositionRace / Ethnicity (NH = Non-Hispanic)Pop 1980Pop 1990Pop 2000Pop 2010 Pop 2020% 1980% 1990% 2000% 2010% 2020White alone (NH)143,652168,071191,753208,742203,28798.27%98.07%96.80%95.43%89.66%Black or African American alone (NH)9521,1881,3401,7762,2950.65%0.69%0.68%0.81%1.01%Native American or Alaska Native alone (NH)2844075436086170.19%0.24%0.27%0.28%0.27%Asian alone (NH)2505266911,4031,8390.17%0.31%0.35%0.64%0.81%Native Hawaiian or Pacific Islander alone (NH)x included in the Asian category in the 1980 Censusx included in the Asian category in the 1990 Census274871xx0.01%0.02%0.03%Other race alone (NH)11437791206220.08%0.02%0.04%0.05%0.27%Mixed race or Multiracial (NH)x not an option in the 1980 Censusx not an option in the 1990 Census1,6642,62812,456xx0.84%1.20%5.49%Hispanic or Latino (any race)9311,1512,0023,4085,5520.64%0.67%1.01%1.56%2.45%Total146,183171,380198,099218,733226,739 100.00%100.00%100.00%100.00%100.00%

2010 census

As of the 2010 census, Jefferson County had a population of 218,733. The reported ethnic and racial make up of the population was 95.4% non-Hispanic white, 0.8% African-American, 0.3% Native American, 0.6% Asian, 0.4% reporting some other race, 1.3% reporting two or more races and 1.6% Hispanic or Latino of any race.2010 census report for Jefferson County, Missouri

2000 census

As of the census of 2000, there were 198,099 people, 71,499 households, and 54,553 families residing in the county. The population density was . There were 75,586 housing units at an average density of . The racial makeup of the county was 97.48% White, 0.68% Black or African American, 0.29% Native American, 0.36% Asian, 0.01% Pacific Islander, 0.24% from other races, and 0.93% from two or more races. Approximately 1.01% of the population were Hispanic or Latino of any race.

There were 71,499 households, out of which 38.90% had children under the age of 18 living with them, 61.00% were married couples living together, 10.40% had a female householder with no husband present, and 23.70% were non-families. 18.90% of all households were made up of individuals, and 6.10% had someone living alone who was 65 years of age or older. The average household size was 2.74 and the average family size was 3.12.

In the county, the population was spread out, with 27.90% under the age of 18, 8.50% from 18 to 24, 31.80% from 25 to 44, 22.50% from 45 to 64, and 9.20% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 98.90 males. For every 100 females age 18 and over, there were 95.90 males.

The median income for a household in the county was $60,636, and the median income for a family was $66,697. Males had a median income of $37,822 versus $25,440 for females. The per capita income for the county was $25,058. About 4.90% of families and 6.80% of the population were below the poverty line, including 8.10% of those under age 18 and 6.30% of those age 65 or over.

There were 146,316 registered voters in 2008. As of October 24, 2012, there were 148,011. Retrieved on July 9, 2013 Education K-12 school districts with territory in the county, no matter how slight, include: - Text list

Crystal City 47 Public Schools De Soto 73 School District Dunklin R-V School District Festus R-VI School District Fox C-6 School District Grandview R-II School District Hillsboro R-3 School District Kingston K-14 School District North St. Francis County R-I School District Northwest R-I School District Meramec Valley School District Rockwood School District Windsor C-1 School District

Additionally, there are two elementary school districts: Jefferson County R-VII School District and Sunrise R-IX School District.

Public schools Crystal City 47 Public Schools - Crystal City Crystal City High School - Crystal City De Soto School District 73 - De Soto Early Childhood Center (PK) Athena Elementary School (K-06) Vineland Elementary School (K-06) De Soto Jr. High School (07-08) De Soto High School (09-12) Dunklin R-V School District - Herculaneum Festus R-VI School District - Festus Festus Elementary School (K-03) Festus Intermediate School (04-06) Festus Middle School (07-08) Festus High School (09-12) Fox C-6 School District - Arnold Grandview R-II School District - Hillsboro Grandview Elementary School (K-05) - Hillsboro Grandview Middle School (06-08) - Hillsboro Grandview High School (09-12) - Ware Hillsboro R-3 School District - Hillsboro Hillsboro Primary School (PK-01) Hillsboro Elementary School (02-03) Hillsboro Intermediate School (04-06) Hillsboro Jr. High School (07-08) Hillsboro High School (09-12) Jefferson County R-VII School District - Festus Plattin Primary School (PK-02) - Plattin Telegraph Intermediate School (03-05) - Festus Danby-Rush Tower Middle School (06-08) - Festus Jefferson High School- Festus Northwest R-I School District - High Ridge Brennan Woods Elementary School (K-05) - High Ridge Cedar Springs Elementary School (K-05) - House Springs High Ridge Elementary School (K-05) - High Ridge House Springs Elementary School (K-05) - House Springs Maple Grove Elementary School (K-05) - Dittmer Murphy Elementary School (K-05) - High Ridge Woodridge Middle School (06-08) - High Ridge Valley Middle School (06-08) - House Springs Northwest High School (09-12) - Cedar Hill Sunrise R-IX School District - De Soto Sunrise Elementary School (K-08) - De Soto Windsor C-1 School District - Imperial

Private schools Christian Outreach School (K-12) - Hillsboro - Nondenominational Christian People's Christian Academy (K-12) - Arnold - Assembly of God/Pentecostal St. Pius X High School (9-12) - Crystal City - Roman Catholic Twin City Christian Academy (PK-12) - Festus - Baptist Good Shepherd Catholic School - (K-08) - Hillsboro - Roman Catholic Holy Child Elementary & Middle School - Arnold - (K-08) - Roman Catholic Manna Christian Academy - De Soto - (K-12) - Southern Baptist Our Lady's Catholic School - Festus - (K-08) - Roman Catholic Sacred Heart Catholic School - Festus - (K-08) - Roman Catholic St. Anthony's Catholic School - High Ridge - (K-08) - Roman Catholic St. Joseph's Catholic School - Imperial - (K-08) - Roman Catholic St. Johns Lutheran School - Arnold - (PK-08) - Lutheran St. Johns School - Imperial - (K-08) - Nondenominational Christianity St. Rose of Lima Catholic School - De Soto - (K-08) - Roman Catholic

Postsecondary Jefferson College - Hillsboro: A public, two-year community college

Public libraries Crystal City Public Library De Soto Public Library Festus Public Library Herculaneum Public Library Jefferson County Public Library

Politics

Local Historically, the Democratic Party has controlled politics at the local level; starting in 2010 the Republican Party has flipped the county with 66% of the population voting Republican in 2020.

State

Jefferson County is divided into seven legislative districts in the Missouri House of Representatives; all of which are held by Republicans. Jefferson County consists of two State Senate Districts.

+ Past gubernatorial elections results Year Republican Democratic Third Parties202466.98% 78,38530.55% 35,7532.47% 2,896202063.91% 73,94233.59% 38,8662.50% 2,886201653.62% 56.75542.74% 45.2343.64% 3,848201241.75% 40,47055.68% 53,9712.56% 2,484200834.42% 35,94763.87% 66,6971.71% 1,781200449.23% 45,89149.25% 45,9091.52% 1,424200047.05% 36,06049.33% 37,8083.62% 2,775199643.90% 28,98652.96% 34,9703.14% 2,077

District 111 Shane Roden (R-Cedar Hill). Consists of Byrnes Mill, Cedar Hill, Cedar Hill Lakes, House Springs, and Scottsdale.

District 112 Rob Vescovo (R-Arnold). Consists of areas near Arnold and Byrnes Mill.

District 113 Dan Shaul (R-Imperial). Consists of most Arnold, all of Imperial and Kimmswick, and part of Barnhart.

District 114 Becky Ruth (R-Festus). Consists of part of Barnhart, and all of Crystal City, Festus, Herculaneum, and Pevely.

District 115 Cyndi Buchheit-Courtway (R-Festus). Consists of Olympian Village and areas near De Soto.

District 118 Mike McGirl (R-Potosi). Consists of De Soto and Hillsboro.

Jefferson County is also divided into two districts in the Missouri Senate.

District 3 — Elaine Gannon (R-De Soto) Consists of De Soto, Hillsboro, and Olympian Village as well as part of Festus.

District 22 — Paul Wieland (R-Imperial) Consists of the northern part of the county.

Federal

Jefferson County is divided among three congressional districts. Prior to the 2012 election all of it was included in Missouri's 3rd Congressional District, but now about half of it is in the 3rd District, while the northeastern portion is in the 2nd Congressional District and the southern portion is in the 8th Congressional District.

Political culture