Prairie du Rocher (“The Rock Prairie” in French) is a village in Randolph County, Illinois, United States. Founded in the French colonial become old in the American Midwest, the community is located close 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.

Prairie du Rocher is one of the oldest communities in the 21st century United States that was founded as a French settlement. About four miles to the west, closer to the Mississippi River, is Fort de Chartres, site of a French military fortification and colonial headquarters conventional in 1720. Some buildings were reconstructed after falling into ruins, and the puzzling is now a declare park and historical site. The fort and town were a center of doling out and commerce at the time as soon as France claimed a gigantic territory in North America, New France or La Louisiane, which stretched from present-day Louisiana and the Illinois Country to Canada.

The village was founded in 1722 by French colonists, mostly migrants from Canada.

In 1718, Pierre Dugué de Boisbriand built the first Fort de Chartres. In 1722, St. Thérèse Langlois, a nephew of Boisbriand, founded Prairie du Rocher. The town was built upon a tract of estate donated by the Royal Indian Company. Boisbriand well along became the commandant of the area. The town was profitably located along fertile Mississippi River bottomland. Surpluses from the productive gardening by habitants later helped supply vital wheat and corn to New Orleans and other belittle Louisiana Territory communities.