Editing St. Charles County, Missouri (section)

===2020 census===
As of 2020, there were 405,262 people and 150,668 households residing in the county. The population density was {{convert|643|PD/sqmi|PD/km2|sp=us|adj=off}}. There were 161,144 housing units. The racial makeup of the county was 83.8% [[White (U.S. Census)|White]], 5.2% [[African American (U.S. Census)|African American]], 0.1% [[Native American (U.S. Census)|Native American]], 2.8% [[Asian (U.S. Census)|Asian]], 0.1% [[Pacific Islander (U.S. Census)|Pacific Islander]], and 6.5% from two or more races. [[Hispanic (U.S. Census)|Hispanic]] or [[Latino (U.S. Census)|Latino]] made up 4.0% of the population.<ref>{{cite web |url=https://data.census.gov/cedsci/profile?g=0500000US29183 |website=United States Census Bureau |access-date=January 9, 2022 |title=St. Charles County, Missouri }}</ref>

There were 101,663 households, out of which 40.50% had children under the age of 18 living with them, 63.20% were [[Marriage|married couples]] living together, 9.20% have a woman whose husband does not live with her, and 24.20% were non-families. 19.40% of all households were made up of individuals, and 5.90% had someone living alone who was 65 years of age or older. The average household size was 2.76 and the average family size was 3.18.

In the county, the population was spread out in age, with 29.00% under the age of 18, 8.20% from 18 to 24, 32.60% from 25 to 44, 21.60% from 45 to 64, and 8.80% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 97.10 males. For every 100 females age 18 and over, there were 94.10 males.

The median income for a household in the county was $71,458, and the median income for a family was $64,415. Males had a median income of $44,528 versus $29,405 for females. The [[per capita income]] for the county was $23,592. 4.00% of the population and 2.80% of families were below the poverty line. Out of the total people living in poverty, 4.90% are under the age of 18 and 5.10% are 65 or older.

St. Charles County has had one of the fastest-growing populations in the state for many decades, with 55% growth in the 1970s, 48% in the 1980s, 33% in the 1990s, and another 27% in the 2000s. The county sits at a cross-section of industry, as well as extensive retail and some agriculture. With the [[Missouri River]] on the south and east and the [[Mississippi River]] on the north, the county is bisected east to west by Interstate 70. After [[St. Charles Airport]] closed in 2010, the county has one remaining small airport, [[St. Charles County Smartt Airport]]. Two ferries cross the Mississippi River from St. Charles County.