State Route 20 (SR-20) runs from the Tennessee state line (State Route 69) northwest of Florence, Alabama, east to I-65 east of Decatur in the northwestern Alabama. It crosses the Tennessee River at Florence (with US-43, US-72, SR-17, and SR-157) and also at Decatur (with US-31 and Alternate US-72)Alternate US-72 follows Highway 20 from the Junction of US-72 at Muscle Shoals to I-65 east of Decatur, the entire stretch being four laned.