SR 81 beings in
Unicoi County at an interchange with
I-26/
US 23/
US 19W (Exit 37) in
Erwin (with the road continuing south as
SR 107). It goes north from this interchange concurrent with SR 107. The two routes leave Erwin and continue north to parallel the
Nolichucky River before crossing into
Washington County. SR 81/SR 107 continue north to pass through
Embreeville, where they cross over a bridge over the Nolichucky River, before entering the community of
Lamar, where SR 107 turns west and SR 81 continues north. SR 81 then crosses a second bridge over the Nolichucky River before having an intersection with
SR 67. The highway then leaves Lamar and the Nolichucky River to continue north through rural farmland before having an intersection with
SR 353 and entering
Jonesborough. SR 81 then enters downtown and has intersections with two roads that provide access to U.S. Routes
11E and
321 and
SR 34, Persimmon Ridge Road and Washington Drive. SR 81 then leaves Jonesborough and continues north through rural areas to junction with
SR 75. SR 81 then continues north for several more miles before coming to an end at
SR 93 about south of
Fall Branch, just about south of its interchange with
I-81. ==Junction list==