St. Charles County, Missouri in the context of "St. Louis Metropolitan Statistical Area"

Greater St. Louis is the 23rd-largest metropolitan statistical area (MSA) in the United States consisting with an MSA population more than 2.8 million, and almost 3 million CSA the largest in Missouri, and the second-largest in Illinois. Its core city—St. Louis, Missouri—sits in the geographic center of the metro area, on the west bank of the Mississippi River. The river bisects the metro area geographically between Illinois and Missouri, although the latter portion is much more populous. The MSA includes St. Louis County, which is independent of the City of St. Louis; their two populations are generally tabulated separately.

The St. Louis, MO-IL metropolitan statistical area (MSA) includes the City of St. Louis; the Illinois counties of Bond, Calhoun, Clinton, Jersey, Macoupin, Madison, Monroe, and St. Clair (known collectively as the Metro East); and the Missouri counties of Crawford (only the City of Sullivan), Franklin, Jefferson, Lincoln, St. Charles, St. Louis (separate from and not inclusive of the city of St. Louis), and Warren.

There are 114 counties and one independent city in the U.S. State of Missouri. Following the Louisiana Purchase and the admittance of Louisiana into the United States in 1812, five counties were formed out of the Missouri Territory at the first general assembly: Cape Girardeau, New Madrid, Saint Charles, Saint Louis, and Ste. Genevieve. Most subsequent counties were apportioned from these five original counties. Six more counties were added through the 1836 Platte Purchase, the acquired lands of which formed the northwest tip of the state and consisted of Andrew, Atchison, Buchanan, Holt, Nodaway, and Platte counties.

In Missouri, the county level of government comes between those of the city and the state. Its primary responsibilities include maintaining roads, providing security, prosecuting criminals, and collecting taxes. Elected officials at this level include a sheriff, prosecuting attorney, and assessor.

Warren County is a county located in the eastern portion of the U.S. state of Missouri. As of the 2020 census, the population was 35,532. The county is located on the north side of the Missouri River. Its county seat is Warrenton. The county was established on January 5, 1833, and was named for General Joseph Warren, who died in the Battle of Bunker Hill during the American Revolutionary War.

Warren County is part of the St. Louis, MO-IL Metropolitan Statistical Area. The county is traversed by Route 94, called the "Missouri Weinstrasse" because of the many vineyards from Marthasville east into St. Charles County. Warren County is also part of the Missouri Rhineland, with award-winning wineries located on both sides of the Missouri River.

Saint Charles (commonly abbreviated St. Charles) is a city in and the county seat of St. Charles County, Missouri, United States. The population was 70,493 at the 2020 census, making St. Charles the eighth-most populous city in Missouri. Situated on the Missouri River near its mouth at the Mississippi, St. Charles is a northwestern suburb of St. Louis.

The city was founded circa 1769 as Les Petites Côtes, or "The Little Hills" in French, by Louis Blanchette, a French-Canadian fur trader. The St. Charles area was settled primarily by French-speaking colonists from Canada in its early days. This former French territory west of the Mississippi River was nominally ruled by Spain following France's defeat in the Seven Years' War, while France had also ceded the east of the Mississippi to Great Britain. St. Charles is thus the third-oldest city in what is now the state of Missouri. In the 18th and 19th century, the city's waterfront played a significant role as a river port for westward trade and expansion, including trade with Native American tribes on the upper Missouri River. In 1804 the Lewis and Clark Expedition considered this settlement the last "civilized" stop before they headed upriver to explore the western territory that the United States acquired from France in the Louisiana Purchase.