Except for a portion roughly between Berry and Russellville, SR 13 is the unsigned designation for U.S. Route 43 (US 43).

The northern terminus of the route is on US 43 at the Tennessee state line north of Killen in Lauderdale County.

As a signed route, the southern terminus of the route is at the intersection of US 43 and SR 18 in southern Fayette County, and the northern terminus as at US 43 and SR 17 south of Russellville in Franklin County.

It leaves the city and continues south for about ten miles to Natural Bridge.

A bypass around Haleyville has been partially built with only the two twin bridges over Little Bear Creek has been completed.