The City of Cairo, Illinois is the southernmost municipality in Illinois, located at the confluence of the Mississippi and Ohio rivers. Cairo is the county seat of Alexander County, and has a population of about 3,600 people - more than a third of the population of the county. Its name is pronounced "CARE-oh", unlike that of the Egyptian city for which it was named.

Cairo, established in 1818, was one of several towns in the region that were named for locations of Classical civilization. Thebes and Karnak are nearby, in Alexander and Pulaski Counties, respectively; further north are Sparta, Lebanon and New Athens; and about one hundred miles south is Memphis, Tennessee, also named for a major Egyptian city. Due to these names, and the resemblance of southern Illinois to the Nile River delta, the region gained the name "Little Egypt".

Cairo City Cemetery is located a few miles north of the city - in Pulaski County, nearer the town of Villa Ridge.