Polco gives each area an index from the public data behind it, adjusted for the community's socioeconomic profile. Higher is stronger by Polco's measure. Where this page has the numbers behind an area, pick it to see them.

Inclusivity and engagement57
Parks and recreation53
Natural environment52
Utilities46

Source: Polco GPAL, using data from the original source shown for each indicator. The area indexes are for 2025.

Data index

What each number actually means.

Pick a number to see how St. Charles County compares with other communities, what Polco's model expected and what to keep in mind.

Where St. Charles County ranks on population

414,535 in 2024

Compared with communities nationallyHigher · 94th percentile

Compared with communities in MissouriHigher · 98th percentile

Compared with communities of similar population sizeHigher · 93rd percentile

Each dot is St. Charles County's percentile within that group, from Polco. Polco treats this measure as neither good nor bad, so further right only means higher.

Source: Polco GPAL, using data from U.S. Census Bureau American Community Survey. Polco’s name for this measure: “Total population”.

What it measures

2024 · Census ACS

How many people live in St. Charles County. The number comes from the Census Bureau's American Community Survey, and college students who live there count as residents.

What Polco's model shows

Model estimate

Polco's GPAL model projects 418,831 for 2025.

Who it affects

More residents means more demand on housing, schools, roads and local services. Population also shapes how much state and federal money St. Charles County receives.

Keep in mind

Survey figures are estimates with a margin of error. Small changes from one year to the next may not be meaningful.

About this data

These figures come from Polco's GPAL data, which brings together public data on U.S. cities and counties from sources like the Census Bureau, the CDC, the Bureau of Labor Statistics and the FBI. Each number is for the year shown with it, and most public data runs one to two years behind. Dollar figures are not adjusted for inflation.

The comparisons are Polco's. Each one names the group of communities St. Charles County is compared with, and the percentile is St. Charles County's place within that group. Polco's model figures are estimates, not measurements.

Polco has 327 measures for St. Charles County. This page shows the 69 whose units and values could be checked. Polco data release of Oct 26, 2026.

Explore St. Charles County on Polco →

Which of these matters most to you?

Tell us, and see how your neighbors answered. Notes and tips go to people covering St. Charles County.