The Shawnee National Forest is a United States National Forest located in the Ozark and Shawnee Hills of Southern Illinois, United States. Administered by the U.S.D.A. Forest Service, it consists of approximately 289,000 acres (1,100 km²) of federally managed lands. In descending order of land area it is located in parts of Pope, Jackson, Union, Hardin, Alexander, Saline, Gallatin, Johnson, and Massac counties. Forest headquarters are located in Harrisburg, Illinois. There are local ranger district offices in Jonesboro and Vienna. The Shawnee National Forest is also the single largest publicly owned body of land in the state of Illinois. It is considered part of Southern Illinois, and is south of the St. Louis, Missouri, and Metro East areas, in area code 618. Portions of it are in the far south area of Illinois known as Little Egypt. Cities in or near the area are Carbondale, Illinois, Marion, Illinois, and Cairo, Illinois.

Southern Illinois is a region of the U.S. state of Illinois comprising the southern third of the state, principally south of Interstate 70. Part of downstate Illinois, it is bordered by the two most voluminous rivers in the United States: the Mississippi below its connection with the Missouri River to the west and the Ohio River to the east and south, with the Wabash as a tributary. Some areas of Southern Illinois are known historically as Little Egypt.