Cairo is a city in Alexander County, Illinois, United States, and serves as the county seat. It is the southernmost city in Illinois, located in the river-crossed area of Southern Illinois. The city is coterminous with Cairo Precinct.
Situated at the confluence of the Mississippi and Ohio rivers, Cairo is a river city with the lowest elevation of any location in Illinois. It is also the state's only city to be surrounded by levees.
The city is named after Egypt's capital on the Nile.