The Withlacoochee River originates in Georgia, northwest of Nashville, Georgia. It flows south through Berrien County where it joins the New River and forms part of the boundary between Berrien and Cook counties. It then flows south into Lowndes County, Georgia. At Troupville, Georgia the Little River joins the Withlacoochee River flows continues to flow south and forms part of the boundary between Lowndes and Brooks counties in Georgia. The river then flows into Florida for 1.34 miles before returning into Georgia for an additional 2.44 miles. It then returns to Florida, forming the northeast boundary of Madison County, Florida and the western boundary of Hamilton County, Florida and eventually merges with the Suwannee at Suwannee River State Park west of Live Oak. The river is 115 miles (185 km) long.

Berrien County is a county located in the south central portion of the U.S. state of Georgia. As of the 2020 census, the population was 18,160. The county seat is Nashville. The county was created February 25, 1856, out of portions of Coffee, Irwin and Lowndes counties by an act of the Georgia General Assembly. It is named after Georgia senator John M. Berrien.