Decatur's main thoroughfares are U.S. Route 31 (6th Avenue), U.S. Route 72 Alternate (S.R. 20), State Route 24, and State Route 67. 6th Avenue begins as both U.S. 72 Alternate and U.S. 31, and the two routes split after being carried by the twin-span "Steamboat Bill" Hudson Memorial Bridge that crosses Tennessee River at the north central part of town. SR 20/Alternate U.S. 72 continues west towards The Shoals and Florence. U.S. 31 connects the city to Athens in the north, and Cullman in the south. A portion of S.R. 67 is known as Beltline Road, and serves as a partial beltway around the city. Interstate 65 runs east of the city, and connects the area to Nashville in the north and Birmingham in the south. Interstate 565 begins in Limestone County northeast of the city, and connects to Huntsville. Transforming U.S. 72 Alternate into an extension of Interstate 565 into the city has been discussed in the past.