St. Louis County, Missouri population
County or county equivalent · Official geographic code 29189
· Annual resident population estimate
U.S. Census Bureau · Population Estimates Program · Vintage 2025
-755 residents (-0.08%) since July 1, 2024.
- Population change, 2020–2025
- -12,454July 1 to July 1 · -1.24%
- Land-area density, 2025
- 1,948.6People per square mile · 2025 land area
- Population rank, 2025
- 53 of 3,144U.S. counties and county equivalents
St. Louis County population history
Open historical explorerThese six July 1 estimates belong to one consistent Vintage 2025 series. The Census Bureau revises earlier years when it releases a new vintage; a figure from an older publication may differ from the value below.
Annual estimates · 2020–2025 · Vertical scale shown on chart.
The highest observed population in this annual series was 1,003,365 in 2020. This is a peak within 2020–2025 coverage, not an all-time record.
| Reference date | Population | Annual change |
|---|---|---|
| July 1, 2020 | 1,003,365 | — |
| July 1, 2021 | 998,850 | -4,515 |
| July 1, 2022 | 991,719 | -7,131 |
| July 1, 2023 | 989,977 | -1,742 |
| July 1, 2024 | 991,666 | +1,689 |
| July 1, 2025 | 990,911 | -755 |
Why is the April 2020 estimates base different from a census count?
The PEP estimates base here is 1,004,548 residents on April 1, 2020. It incorporates the Census Bureau’s corrections and geographic revisions and serves as the starting point for this annual series. It is not labeled an original 2020 census count. The chart starts at July 1, 2020, so its five-year change uses two July observations. Read about measurement types.
Growth and density
Between July 1, 2020 and July 1, 2025, St. Louis County lost 12,454 residents, a 1.24% decrease. The annualized change over these five elapsed years was -0.25%. Annualized change is a summary of the interval; it does not imply that the population changed at that rate in every year.
The 2025 Gazetteer reports 508.53 square miles of land. Dividing the July 1, 2025 population by that compatible land area gives 1,948.6 people per square mile. Water area is excluded. Density depends on geographic boundaries. It describes this entire geography, rather than a typical neighborhood or built-up area.
Calculations use unrounded source values. Population counts are displayed as integers, percentages to two decimals and density to one decimal. Calculation methods · Growth calculator
Components of population change
The published components cover July 1, 2024 through June 30, 2025. Natural change equals births minus deaths. Net migration is arrivals minus departures; it does not establish why people moved.
| Component | People |
|---|---|
| Births | 9,583 |
| Deaths | 10,899 |
| Natural change | -1,316 |
| Net domestic migration | -3,370 |
| Net international migration | +3,895 |
| Residual | +36 |
| Total population change | -755 |
Reconciliation: natural change + net domestic migration + net international migration + residual = -755. Births and deaths are already included in natural change and must not be added again. Source: co-est2025-alldata.csv; Vintage 2025.
Age structure, race and Hispanic-origin panels are not included in this totals release. Their separate periods, definitions and uncertainty will be validated before publication. Coverage details.
Geographic context
County equivalents include parishes, boroughs, census areas, independent cities, DC and Connecticut planning regions where represented by Census. The places listed below are whole-city observations and can extend into other counties. Summing them will not reproduce this county total.
| Place | Population · 2025 | Change · 2024–25 | Growth · 2024–25 | People / sq. mi. |
|---|---|---|---|---|
| FlorissantMissouri · Incorporated place · 2924778 | 51,124 | -107 | -0.21% | 4,073.1 |
| ChesterfieldMissouri · Incorporated place · 2913600 | 49,309 | -63 | -0.13% | 1,550.1 |
| WildwoodMissouri · Incorporated place · 2979820 | 34,955 | -41 | -0.12% | 521.4 |
| University CityMissouri · Incorporated place · 2975220 | 34,657 | +342 | +1.00% | 5,892.6 |
| BallwinMissouri · Incorporated place · 2903160 | 30,901 | -91 | -0.29% | 3,401.5 |
| KirkwoodMissouri · Incorporated place · 2939044 | 29,331 | +17 | +0.06% | 3,194.3 |
| Maryland HeightsMissouri · Incorporated place · 2946586 | 27,559 | -71 | -0.26% | 1,259.5 |
| HazelwoodMissouri · Incorporated place · 2931276 | 24,849 | -75 | -0.30% | 1,549.4 |
| Webster GrovesMissouri · Incorporated place · 2978154 | 23,450 | -61 | -0.26% | 3,966.8 |
| Creve CoeurMissouri · Incorporated place · 2917272 | 18,480 | -28 | -0.15% | 1,798.5 |
Showing 10 of 87 related records.
Missouri population · State city directory · City proper versus county versus metro
Places with nearby population ranks
Selected from the same 2025 comparison universe, using neighboring population ranks. Similar population does not imply similar density, boundaries or demographics.
| Place | Population · 2025 | Change · 2024–25 | Growth · 2024–25 | People / sq. mi. |
|---|---|---|---|---|
| Capitol Planning RegionConnecticut · County equivalent · 09110 | 994,115 | +4,921 | +0.50% | 967.6 |
| Marion CountyIndiana · County equivalent · 18097 | 992,196 | +1,983 | +0.20% | 2,505.6 |
| Honolulu CountyHawaii · County equivalent · 15003 | 988,703 | -1,439 | -0.15% | 1,645.7 |
| Bergen CountyNew Jersey · County equivalent · 34003 | 977,026 | +3,549 | +0.36% | 4,196.9 |
Source, citation and downloads
U.S. Census Bureau, Population Estimates Program, Vintage 2025, co-est2025-alldata.csv, variable POPESTIMATE2025; St. Louis County, Missouri, geographic code 29189; resident population 990,911 on July 1, 2025; boundaries January 1, 2025. https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/counties/totals/co-est2025-alldata.csv. Retrieved September 30, 2026. US Population Data snapshot pep-2025-r1, transformation 1.
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