US 231-431 BUS begins as a continuation along AL 1 (South Oates Street) at the Ross Clark Circle (Alabama State Route 210), where mainline US 231 moves to the west and US 431 begins at the east.

Sharing the dual name of Martin Luther King Junior Boulevard, US 431 BUS/SR 1 immediately crosses a bridge over another railroad line between two rail yards.

It makes a slight curve to the north-northeast between Headland Avenue and Bic Road.

The route consists of a four-lane divided highway named College Road branching off to the northwest, and suddenly terminates at Paden Road near the Koch Foods manufacturing factory.

At both of its termini, there are signs stating that there is a US 431 Business in Franklin as well, even though this designation doesn’t exist and this is mainline US 431 through the city.