The highway travels northeast–southwest through the state, crossing into Louisiana approximately 23 miles northeast of Carthage.

US 79 runs through the town of Rockdale before entering Milano, where it begins an overlap with U.S. Route 190 and a brief concurrency with State Highway 36.

The highway runs through several smaller towns, including Franklin and Buffalo, and begins an overlap with US 84 approximately 9 miles southwest of Palestine.

Leaving Palestine, US 79 travels through a heavily forested area of east Texas serving the towns of Jacksonville and Henderson.

About 23 miles northeast of Carthage US 79 leaves Texas and enters into Louisiana, running towards Shreveport.