An official alternate route is a special route in the United States that provides an alternate alignment for a highway.
They are loop roads and found in many road systems in the United States including the U.S. Highway system and various state and county route systems.
[citation needed] In some cases, an additional business route exists as a third alignment, as with former U.S. Route 71 Alternate, which bypassed Joplin, Missouri.
It is further recommended that the Highway Department erect signs at the junction points of the regular and alternate routes giving the distance between the cities or points concerned...
In no instance should an alternate routing be used for the purpose of keeping an obsolete section on the U.S. numbered system after a new routing has been constructed and available to traffic.