Carbondale is a city in Jackson County, Illinois, United States, within the Southern Illinois region informally known as "Little Egypt". As of the 2020 census, the city had a population of 25,083, making it the most populous city in Southern Illinois outside the Metro East region of Greater St. Louis. Carbondale was established in 1853 and developed as a crossroads of the railroad industry. Today, the major roadways of Illinois Route 13 and U.S. Route 51 intersect in the city.