. The American Association of State Highway Officials (AASHO) adopted a resolution in opposition to split routes in 1934.
. In order to get rid of the US 31E/US 31W split, it specially made a new U.S. Route 37, which replaces US 31E from Louisville area south to Glasgow, and after that it follows the Kentucky Route 63 and quite a lot of routes in Tennessee to Chattanooga.
. The rest of US 31E, starting from Glasgow to Nashville, was assigned U.S. Route 143; this proposed route has been extended from southwest to Centerville in 1938 and Jackson in 1944 via State Route 100 as well as State Route 20.
. US 31W become the mail route of US 31, in which Kentucky and Tennessee refused to accept the renumbering, and in no way they changed there signs, leading American Association of State Highway Officials (AASHO) to re-recognize the split in 1952.