SR 104 begins as a secondary highway in Dyer County on the banks of the Mississippi River. It goes east to have an intersection with SR 181 before crossing over the Obion River to pass through Finley, where it has an intersection with SR 182. The highway now enters Dyersburg and passes through industrial areas before having an intersection with US 51/SR 3. SR 104 then passes through neighborhoods before entering downtown along Forrest Street to have an intersection with SR 78, where it becomes McGaughey Street. It then becomes concurrent with US 51 Bus./SR 211 for a short distance as it turns south along N Main Avenue before splitting off and going east along E Court Street. The highway passes through more neighborhoods before coming to an interchange with US 412/SR 20, where SR 104 leaves Dyersburg and becomes a primary highway. SR 104 passes through RoEllen before crossing into Gibson County via a bridge over the North Fork of the Forked Deer River. The entire route of SR 104 in Dyer County is a two-lane highway.
Gibson County
SR 104 then passes through Eaton, where it has an intersection with SR 188, before widening to a 4-lane divided highway as it continues east through farmland to come to an intersection with SR 457, where it narrows to 2-lanes and enters Trenton. It passes through downtown along Eaton Street, where it has an intersection with SR 367, before coming to an intersection with US 45W/SR 43/SR 54/SR 77. SR 104 now becomes concurrent with SR 77, where SR 104 becomes unsigned, and they leave Trenton and cross another bridge over the North Fork of the Forked Deer River. SR 77/SR 104 pass by Gibson County Airport before entering Milan as N Main Street. They pass through neighborhoods before making a left onto Front Street to come to an intersection and become concurrent with US 45E/SR 43, where SR 77 also becomes unsigned. They pass through downtown as a 4-lane undivided highway to come to an intersection with US 70A/US 79/SR 76, where SR 77 splits off follows that highway. SR 104 splits off from US 45E/SR 43 a short distance later along Ellington Drive as a signed secondary highway. SR 104 goes east as a 2-lane highway to leave Milan and cross into Carroll County.
Carroll County
SR 104 passes through rural and slightly hilly terrain as it has a short concurrency with SR 220 before coming to an intersection with US 70/SR 1. It turns southeast, along US 70/SR 1, to pass through Cedar Grove, where it has another intersection with SR 220 before SR 104 splits off and goes southeast to cross into Henderson County.
Henderson and Hardin Counties
SR 104 becomes very curvy as it passes through hilly terrain to have an interchange with I-40. It then continues southeast through farmland to enter Lexington and pass along the western shore of Beech Lake to come to an intersection and become concurrent with US 412/SR 20. They pass just south of the Beech River Dam and cross over the Beech River as a 4-lane undivided highway to pass through a business district before entering downtown to have an intersection with SR 22 before SR 104 splits off at an intersection with SR 114. The highway then makes a left onto S Main Street and heads southeast to have another crossing of the Beech River to leave Lexington as a 2-lane highway to pass through hilly and wooded areas. SR 104 then passes through Reagan, where it has an intersection with SR 100, before passing through the town of Sardis, where it has a concurrency with SR 201 and an intersection with SR 421. The highway continues southeast to cross into Hardin County and come to an end at an intersection with SR 69 at the western edge of Saltillo.
