Murphysboro is located in southern Illinois in Jackson County (of which it is the county seat) southwest of Mt. Vernon just north of Carbondale at the junction of Highways 13 and 127 near Kinkaid Lake. It is situated just east of the Mississippi River and only minutes north of the Shawnee National Forest. The population estimate for July 1, 1998 was 8,950, a decrease of 226 since 1990.