The Doe River forms in Carter County, Tennessee near the North Carolina line just south of Roan Mountain State Park. It initially flows north and is first paralled by Tennessee Highway 143; at the community of Roan Mountain, Tennessee it begins to flow west and is at this point paralled by U.S. Highway 19E. It flows to the east of Fork Mountain; the Little Doe River flows by it to the west. Below the confluence of the two streams at Hampton , the stream flows roughly north, rejoined by U.S. 19E. Flowing through a mountain gap just north of Hampton, the flow of the stream is increase somewhat by the waters of a major spring, McCathern Spring. Just before its mouth into the Watauga River in the Carter County seat of Elizabethon it is crossed in the downtown area of that city by a renowed covered bridge. The valley of the Doe is subject to frequent and severe flooding. The mountainous area which it drains can be subject to frequent and heavy rains, and the stream's course is quite steep, allowing water levels to rise relatively rapidly.