Randolph County is a county located in the U.S. state of Illinois. According to the 2020 census, it had a population of 30,163. Its county seat is Chester.
Owing to its role in the state's history, the county motto is "Where Illinois Began." It contains the historically important village of Kaskaskia, Illinois's first capital.
Kaskaskia is a village in Randolph County, Illinois, on the west side of the Mississippi River. The population of Kaskaskia was 21 in the 2020 United States census, making it the third-least populous incorporated community in Illinois behind Valley City (pop. 14) and Florence (pop. 17). Kaskaskia has an Illinois telephone area code (618) and a Missouri ZIP Code (63673). Its roads are maintained by Illinois Department of Transportation, and its few residents vote in Illinois elections. The town was evacuated in the Great Flood of 1993, which covered it with water more than 9 ft (3 m) deep.
St. Clair County is the ninth most populous county in Illinois. Located directly east of St. Louis, the county is part of the Metro East region of the Greater St. Louis metropolitan area in southern Illinois. As of the 2020 United States census, St. Clair County had a population of 257,400, making it the second most populous county in Illinois outside the Northern Third. Belleville is the county seat and largest city.
Along the Mississippi River, Cahokia Village was founded in 1697 by French settlers and served as a Jesuit mission to convert tribes of the Illinois Confederation to Christianity. The area became the center of the French Illinois Country. Prior to the establishment of Illinois as a state, the government of the Northwest Territory created St. Clair County in 1790. In 1809, the county became the administrative center of the Illinois Territory and one of the two original counties of Illinois, alongside Randolph County. In 1970, the United States Census Bureau placed the mean center of U.S. population, which generally has moved west every decennial census, in St. Clair County.
Fort de Chartres was a French fortification first built in 1720 on the east bank of the Mississippi River in present-day Illinois. It was used as the administrative center for the province, which was part of New France. Due generally to river flooding, the fort was rebuilt twice, the last time in limestone in the 1750s in the era of French colonial control over Louisiana and the Illinois Country.
The magazine (ammunition storehouse) of the fort is believed to be the oldest surviving building in Illinois. A partial reconstruction now exists of the limestone fort and the site is preserved as an Illinois state park, four miles (6 km) west of Prairie du Rocher in Randolph County, Illinois. Located on the floodplain area that became known as the American Bottom, the site is south of modern St. Louis. The forts were placed on the National Register of Historic Places and recognized as a National Historic Landmark on October 15, 1966. It was named one of the contributing properties to the French Colonial Historic District in 1974, along with other French-influenced sites such as the Creole House, the Pierre Menard House, the Kolmer Site (a former Indian village), and the site of Fort Kaskaskia.
Prairie du Rocher ("The Rock Prairie" in French) is a village in Randolph County, Illinois, United States. Founded in the French colonial period in the Midwest, the community is located near bluffs that flank the east side of the Mississippi River along the floodplain often called the "American Bottom". The population was 502 at the 2020 census.
The Creole House is a historic residence in the village of Prairie du Rocher, an old French settlement in present-day Randolph County, Illinois, United States. Built at the end of the eighteenth century and later expanded, the Creole House is the last survivor in Illinois of its type of vernacular architecture, and it forms an important part of the built environment of a portion of the Upper Mississippi Valley that possesses an unparalleled connection to the French settlement period.
The Kolmer Site is an archaeological site in the far southwest of the U.S. state of Illinois. Located near Kaskaskia and Prairie du Rocher in western Randolph County, it lies at the site of an early historic Indian village from the French period. Because it occupies a critical chronological and cultural position, it has been given national recognition as a historic site.