Alternate route

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. Alternate routes were created as a means of connecting a town (or towns) desired to be on a route that had been routed differently to put another important town or city on the route, or, in the case of the U.S. Highway system, as a means to eliminate divided routes.

The term "optional route" has also been used. In some cases, an additional business route exists as a third alignment, as with former U.S. Route 71 Alternate, which bypassed Joplin, Missouri.

AASHTO defines and specifies that alternate routes of the US Route system shall have the following behavior:

In at least one case, the banner "Optional Route" was retained when a second alternate route existed. One example occurred in Kansas City, Missouri, with U.S. Route 40, which had an alternate and an optional route simultaneously.

In some US states, an alternate route will be designated by adding an "A" after the number instead of a sign marked "Alternate" above it: "US 69A" means "US 69 Alternate".

• U.S. Roads portal
• List of business routes of the Interstate Highway System
• Bypass (road)
• List of special routes of the United States Numbered Highway System