4.00% of the population and 2.80% of families were below the poverty line.
The per capita income for the county was $23,592. Males had a median income of $44,528 versus $29,405 for females. The median income for a household in the county was $71,458, and the median income for a family was $64,415. For every 100 females age 18 and over, there were 94.10 males. For every 100 females there were 97.10 males. 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 average household size was 2.76 and the average family size was 3.18. 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. There were 101,663 households, out of which 40.50% had children under the age of 18 living with them, 63.20% were married couples living together, 9.20% have a woman whose husband does not live with her, and 24.20% were non-families. Hispanic or Latino made up 4.0% of the population. The racial makeup of the county was 83.8% White, 5.2% African American, 0.1% Native American, 2.8% Asian, 0.1% Pacific Islander, and 6.5% from two or more races. The population density was 643 people per square mile (1665/km 2).
Peters where the Interstate widens to 11 lanes of traffic. It is mostly a six-lane freeway in the county, but there are sections in St. I-70 – The major east–west thoroughfare in the county.The highway was re-signed as Interstate 64 from the Daniel Boone Bridge to Interstate 70 in Wentzville in 2009. Route 40, the highway was upgraded to Interstate standards in the late 2000s. I-64 – Major freeway in the western portion of the county.The highest elevation is 901 feet (275 m) northwest of Augusta near Femme Osage Creek headwaters. Census Bureau, the county has a total area of 593 square miles (1,540 km 2), of which 560 square miles (1,500 km 2) is land and 32 square miles (83 km 2) (5.4%) is water. Charles County is the only known habitat of the threatened decurrent false aster in Missouri. The county's rural outer edge along the south-facing bluffs above the Missouri River, is also part of the broader Missouri Rhineland. Charles County includes a part of the Augusta AVA, an area of vineyards and wineries designated by the federal government in 1980 as the first American Viticultural Area. Charles County is one of the nation's fastest-growing counties. Louis, MO- IL Metropolitan Statistical Area and contains many of the city's northwestern suburbs. The county was organized October 1, 1812, and named for Saint Charles Borromeo, an Italian cardinal. As of the 2020 census, the population was 405,262, making it Missouri's third-most populous county. Charles County is in the central eastern part of the U.S.