SR 90 begins in northern
Campbell County at an
intersection with
U.S. Route 25W (US 25W) in the community of
Morley, north of
LaFollette and southeast of
Jellico. The route then twists and turns through the
Cumberland Mountains of northern Tennessee, climbing through a series of
switchback curves to the top of Hickory Hill, where it passes through
White Oak. After descending from this ridge to
Tackett Creek, the highway veers northeastward into the Clearfork Valley, where it traverses the communities of
Anthras,
Eagan, and
Clairfield. It comes to an end at
Kentucky Route 74 at the
Kentucky state line in the old mining community of
Pruden. KY 74 continues eastward through rugged mountain terrain to
Middlesboro, Kentucky. The route crosses the
Clear Fork River twice and parallels the river for much of its length. ==Major intersections==