[3] Highway 303 begins at Highway 45 at Mayfield and runs north through unincorporated Washington County to meet US Route 412 at Spring Valley near the historic Spring Valley School.

The two routes participate in a 1 mile (1.6 km) concurrency east until Highway 303 turns north from US  412 near the Madison County line.

The route then runs north towards War Eagle and becomes Benton CR 98 which eventually gives access to Highway 12 near Beaver Lake.

[4] Highway 303 begins at Highway 12, angling northeast before terminating at Rocky Branch Road (Benton CR 99) near the Rocky Branch School and Beaver Lake.

[1] Initially only the portion from Mayfield to the Benton County line was transferred to state maintenance.