Metropolis is a city located along the Ohio River in Massac County, Illinois, United States. As of the 2020 census, it had a population of 5,969, down from 6,537 in 2010. Metropolis is the county seat of Massac County and is part of the Paducah, KY-IL Metropolitan Statistical Area in Southern Illinois.

The Ohio River is a 981-mile-long (1,579 km) river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing in a southwesterly direction from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illinois. It is the third largest river by discharge volume in the United States and the largest tributary by volume of the north-south flowing Mississippi River, which divides the eastern from western United States. It is also the 6th oldest river on the North American continent. The river flows through or along the border of six states, and its drainage basin includes parts of 14 states. Through its largest tributary, the Tennessee River, the basin includes several states of the southeastern U.S. It is the source of drinking water for five million people.