Metro Lakeland is a name that was coined in the 1960s for an area of southern Illinois that is centered on the intersections of Interstate 57, Interstate 24, and Illinois Route 13 — a four-lane east-west highway connecting the communities of Murphysboro, Carbondale, Carterville, Herrin, Marion, and Harrisburg. Metro Lakeland was defined as Jackson, Williamson, Franklin, Saline, and Perry counties, with a combined population of approximately 210,000. Carbondale, Herrin, and Marion are the key urban areas, with a combined city-proper population of over 65,000 (2007 Census estimate) Carbondale, the site of Southern Illinois University, is the region's largest city. Metro Lakeland is about southeast of St. Louis, Missouri, or by Interstate highway.