St. Charles County is in the central eastern part of the U.S. state of Missouri. As of the 2020 census, the population was 405,262, making it Missouri's third-most populous county. Its county seat is St. Charles. The county was organized October... Wikipedia
Cities: Saint Charles, St. Peters, Wentzville, and more
Population: 413,803 (2022)
Congressional districts: 2nd, 3rd
Founded: October 1, 1812
Largest city: O'Fallon
Seat: St. Charles