Prairie du Rocher, Illinois (“The Rock Prairie” in French) is a village in Randolph County, Illinois. Founded in the French colonial period in the American Midwest, the community is located near bluffs that flank the east side of the Mississippi River along the floodplain often called “American Bottom.”

Prairie du Rocher is the one of the oldest communities in the 21st century U.S. 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 established in 1720. The fort and town were a center of government and commerce at the time when France claimed a vast territory in North American, New France or La Louisiane, which stretched from present-day Louisiana and the Illinois Country to Canada.