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St. Louis County, Missouri facts for kids

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Saint Louis County
St. Louis County
Babler State Park, the largest of three state parks in St. Louis County
Babler State Park, the largest of three state parks in St. Louis County
Official seal of Saint Louis County
Map of Missouri highlighting Saint Louis County
Location within the U.S. state of Missouri
Map of the United States highlighting Missouri
Missouri's location within the U.S.
Country  United States
State  Missouri
Founded October 1, 1812
Seat Clayton
Largest city Florissant
 • Total 523 sq mi (1,350 km2)
 • Land 508 sq mi (1,320 km2)
 • Water 15 sq mi (40 km2)  2.9%
 • Estimate 
Time zone UTC−6 (Central)
 • Summer (DST) UTC−5 (CDT)
Congressional districts 1st, 2nd

St. Louis County is located in the eastern-central portion of 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 total population was 1,004,125, making it the most populous county in Missouri. Its county seat is Clayton. 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.

In 1877 residents of the City of St. Louis voted to separate from the county and become an independent city. In the 1960s, with growing suburban development of Greater St. Louis, the county's population overtook that of the city for the first time. Restructuring of industry resulted in job and population declines in the city, and the county has continued to expand.

Through the decades changing conditions have led many business and political leaders to propose merging the city and county as a single government. In 2019 there was an effort to put the issue to a state-wide vote, but it did not get on a ballot.


As of 2009, the largest employment sectors in St. Louis County are education and health (25.2%), trade and transportation (19.6%), and professional business services (12.7%). The county also has the highest per capita income in Missouri ($49,727), and nearly one-fourth of the state workforce is employed in St. Louis County, but it accounts for 27% of the state's wages. It is home to the eighth-strongest market for technology hiring, and the world's largest concentration of plant science Ph.D.'s. The St. Louis County Economic Council is the economic development agency of St. Louis County, and it is operated under the authority of the St. Louis County government. Among the largest employers in the county are Boeing (16,000 employees), Washington University in St. Louis (13,200 employees), and SSM Healthcare (12,400 employees). As of 2013, Express Scripts has approximately 4,500 employees, with a planned expansion of 1,500 jobs to be added over the five years from 2013 to 2018.

Unemployment in St. Louis County is well below the national rate of 7.7% (November 2012) at 6.5% (October); for monthly unemployment numbers since June 2012, see below:


Historical population
Census Pop.
1820 10,049
1830 14,125 40.6%
1840 35,979 154.7%
1850 104,978 191.8%
1860 190,524 81.5%
1870 351,189 84.3%
1880 31,888 −90.9%
1890 36,307 13.9%
1900 50,040 37.8%
1910 82,417 64.7%
1920 100,737 22.2%
1930 211,593 110.0%
1940 274,230 29.6%
1950 406,349 48.2%
1960 703,532 73.1%
1970 951,353 35.2%
1980 973,896 2.4%
1990 993,529 2.0%
2000 1,016,315 2.3%
2010 998,954 −1.7%
2020 1,004,125 0.5%
Independent City of St. Louis seceded
from the County in 1876. Population
of the City of St. Louis in 1880
was 350,518.
U.S. Decennial Census
1790–1960 1900–1990
1990–2000 2010–2019

As of the census of 2010, there were 998,954 people. There were 404,765 households with 263,423 family households. The population density was 1,966 people per square mile (773/km2). There were 423,749 housing units at an average density of 834 per square mile (322/km2). The racial makeup of the county was 68.3% White (66.9% Non-Hispanic White), 35.3% African American, 0.2% Native American, 3.5% Asian (1.1% Asian Indian, 1.0% Chinese, 0.3% Filipino, 0.3% Korean, 0.3% Vietnamese, 0.1% Japanese, 0.4% Other), 0.03% Pacific Islander, 0.9% from other races, and 1.9% from two or more races and 2.5% Hispanic or Latino (1.5% Mexican, 0.2% Puerto Rican, 0.1% Cuban, 0.8% Other).

There were 404,765 households, out of which 31.0% had children under the age of 18 living with them, 51.00% were married couples living together, 12.70% had a female householder with no husband present, and 33.00% were non-families. 28.00% of all households were made up of individuals, and 10.10% had someone living alone who was 65 years of age or older. The average household size was 2.47 and the average family size was 3.05.

In the county, the age distribution of the population shows 25.20% under the age of 18, 8.30% from 18 to 24, 29.00% from 25 to 44, 23.50% from 45 to 64, and 14.10% who were 65 years of age or older. The median age was 38 years. For every 100 females, there were 90.00 males. For every 100 females age 18 and over, there were 85.70 males.

The median income for a household in the county was $58,532, and the median income for a family was $72,680. Males had a median income of $45,714 versus $30,278 for females. The per capita income for the county was $27,595. About 5.00% of families and 6.90% of the population were below the poverty line, including 9.30% of those under age 18 and 5.30% of those age 65 or over.

Racial composition 2010 2020
White 70.3% 63.0%
—Non-Hispanic 68.9% 62.2%
Black or African American 23.3% 24.6%
Hispanic or Latino (of any race) 2.5% 3.7%
Asian 3.5% 4.9%
Two or More Races 1.9% 5.7%


Education in St. Louis County is provided by 24 school districts, private schools, both a unified public library system and several municipal libraries, and several colleges and universities.

School districts operating within St. Louis County include Affton, Bayless, Brentwood, Clayton, Ferguson-Florissant, Hancock Place, Hazelwood, Kirkwood, Jennings, Ladue, Lindbergh, Maplewood-Richmond Heights, Mehlville, Normandy, Parkway, Pattonville, Ritenour, Riverview Gardens, Rockwood, Special School District, University City, Valley Park, and Webster Groves. Several of the school districts in the county also maintain a voluntary student transfer agreement with the St. Louis Public Schools that allows county residents to attend magnet schools in the city of St. Louis. In addition to public school districts, several private schools operate in the county. These include independent secular and religious schools, and Catholic parochial schools operated by the Archdiocese of St. Louis.

St. Louis County libraries include the unified St. Louis County Library and several municipal library systems.

Colleges and Universities

Public and non-profit private colleges and universities in St. Louis County include Concordia Seminary, Eden Theological Seminary, Fontbonne University, Kenrick–Glennon Seminary, Logan College of Chiropractic, Maryville University, Missouri Baptist University, University of Missouri–St. Louis, St. Louis Christian College, three campuses of the St. Louis Community College, Washington University in St. Louis, St. Louis University, and Webster University.



Major freeways and highways

  • I-44
  • Business Loop 44.svg Interstate 44 Business
  • I-55
  • I-64
  • I-70
  • I-170
  • I-255
  • I-270
  • US 40
  • US 50
  • US 61
  • US 66 (1926–1979)
  • US 67
  • Route 21
  • Route 30
  • Route 100
  • Route 115
  • Route 141
  • Route 180
  • Route 231
  • Route 267
  • Route 364
  • Route 366
  • Route 367
  • Route 370

Images for kids

See also

Kids robot.svg In Spanish: Condado de San Luis para niños

Black History Month on Kiddle
African-American Women in Medicine:
Mary Eliza Mahoney
Susie King Taylor
Ida Gray
Eliza Ann Grier
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