The Green River in Tennessee is one of the main streams of Wayne County. Wayne County, in the southwestern corner of Middle Tennessee along the Alabama line, is one of the state's largest counties in area but is very sparsely populated. Most of the county is located on the Southern Highland Rim, an area of hills, ridges, and narrow stream valleys that is largely underlain by Paleozoic limestone. The Green River rises about seven miles southeast of the Wayne County seat of Waynesboro and flows northwest into that town, which is almost bisected by it, and then flows generally almost due north, albeit by a fairly meandering course, to its confluence with the Buffalo River just south of the Wayne County - Perry County line. It is the source of the Waynesboro municipal water supply. The river lives up to its name, often showing a deep bluish-green color, especially in its downstream reaches.