Region Four is located in the southeastern United States bordering both the Atlantic Ocean and the Gulf of Mexico The region consists of the following states: Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina and Tennessee.

Important water bodies within this region include the Florida Everglades, the Cahaba River, Mobile Bay, the Caloosahatchee River, the Chattahoochee River and the Ogeechee-Canoochee River.