St. Charles County, Missouri Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 3rd-largest in Missouri
The population of St. Charles County, Missouri is 409,830 as of the 2023 American Community Survey, making it the 3rd-largest county in Missouri. The median household income is $102,912, the median home value is $296,800, and the median age is 39.6.
The population of St. Charles County has grown 17.1% since 2010 (361,808 → 423,726), a +1.13% annualized rate.
409,830
Population
+1.13%
Annual growth
731
People / sq mi
$102,912
Median Income
$296,800
Median Home Value
St. Charles County covers 561 sq mi of land at 731.2 people per square mile.
About St. Charles County, MO
The poverty rate is what most separates St. Charles County from the typical county: 3.0% of residents live below the federal poverty line, against 12.4% nationally. With 409,830 residents, St. Charles County is a county in Missouri. It is the #3-largest of all counties in Missouri nationally.
Income is a real outlier — the median household pulls in $102,912, putting St. Charles County near the top of US counties. Very few residents live in poverty — 3.0%, below the national 12.4%. The median home value is $296,800, with typical rent around $1,312.
The population is unusually well-credentialed for US counties — 42.4% of adults have a four-year degree, above the national 35.0%. Remote work is widespread — 16.0% of workers stay home, above the national 14.0%, and the average commute runs about 25 minutes each way.
St. Charles County Population History (2010-2024)
The county of St. Charles County had a population of 361,808 in 2010 and 423,726 in 2024, a 17.1% growth over 14 years. The peak was 423,726 in 2024. Average annual growth rate: 1.14%.
423,726
Population (2024)
361,808
Population (2010)
423,726
Peak (2024)
1.14%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 361,808 |
| 2011 | 365,614 |
| 2012 | 369,175 |
| 2013 | 374,378 |
| 2014 | 379,956 |
| 2015 | 385,108 |
| 2016 | 390,724 |
| 2017 | 395,153 |
| 2018 | 398,656 |
| 2019 | 401,625 |
| 2020 | 406,423 |
| 2021 | 410,515 |
| 2022 | 414,055 |
| 2023 | 417,958 |
| 2024 | 423,726 |
Race & Ethnicity
| White | 85.0% |
| Black or African American | 5.1% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 0.9% |
| Two or More Races | 0.0% |
Age & Sex
39.6
Median Age
50.6%
Female
49.4%
Male
16.4%
Age 65+
Age Distribution
Children (under 15): 18.6% · Seniors (65+): 16.4%
Income & Poverty
| Median household income | $102,912+$33,992 vs state |
| Mean household income | $127,112 |
| Per-capita income | $49,859 |
| Poverty rate | 3.0%-5.4% vs state |
| Unemployment rate | 2.0% |
| Employment-to-population | 67.3% |
Top Industries by Employment
The largest employment sector in St. Charles County is professional & business services, accounting for 21.6% of workers.
How residents commute
0.1%
Drive alone
0.7%
Carpool
76.2%
Public transit
16.0%
Work from home
24.9 min
Avg commute
Housing
$296,800+$81,200 vs state
Median home value
$1,312
Median rent
80.7%
Homeownership rate
164,594
Total housing units
96.4%
Occupied
3.6%
Vacant
19.3%
Renter-occupied
Social & access
95.7%
With health insurance
97.0%
With broadband internet
26.2%
Foreign-born
6.8%
Veterans (18+)
11.1%
With a disability
94.5%
Speak language other than English at home
Education
95.5%
High School+
42.4%
Bachelor's+
Largest cities in Missouri
Other counties in Missouri
Part of Missouri
Metro areas in Missouri
County rankings
Common questions about St. Charles County, MO
Frequently Asked Questions
St. Charles County, Missouri has a population of 409,830 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 3rd-largest county in Missouri. Population density is 731 people per square mile.
The population of St. Charles County has grown 17.1% since 2010 (361,808 → 423,726), a +1.13% annualized rate.
The median household income in St. Charles County, Missouri is $102,912, with mean (average) household income of $127,112 and per-capita income of $49,859. 3.0% of residents live below the federal poverty level.
In St. Charles County, the largest racial and ethnic groups are White (85.0%), Black or African American (5.1%), Hispanic or Latino (0.9%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in St. Charles County, Missouri is 39.6 years. Residents are 50.6% female and 49.4% male.
The median home value in St. Charles County is $296,800 and median monthly rent is $1,312. 80.7% of occupied housing units are owner-occupied. The county has 164,594 total housing units, 3.6% of which are vacant.
The largest employment sector in St. Charles County, Missouri is professional, scientific, and management services, employing 21.6% of workers. The unemployment rate is 2.0%.
Kansas City is among the largest cities associated with St. Charles County, Missouri, with a population of 508,233.
St. Charles County, MO Climate
St. Charles County, MO has an average annual temperature of 12.8°C (55°F) and receives about 957 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
12.8°C
Avg Temp
957
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -2° / 29° | 45 mm |
| February | 1° / 34° | 51 mm |
| March | 7° / 44° | 85 mm |
| April | 13° / 55° | 94 mm |
| May | 18° / 65° | 107 mm |
| June | 23° / 74° | 89 mm |
| July | 26° / 79° | 100 mm |
| August | 25° / 76° | 80 mm |
| September | 21° / 69° | 82 mm |
| October | 14° / 57° | 75 mm |
| November | 7° / 45° | 81 mm |
| December | 1° / 33° | 68 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit St. Charles County, MO
The most comfortable months to visit St. Charles County, MO are typically September, June and August, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 32°C high). The coldest is January (near -7°C low). May is usually the wettest month.
Where to stay near St. Charles County
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Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.