The second branch of Route 66, US Highway 266, was part of the Joint Board of Interstate Highways’ 1925 recommendations for branch routes of US 66. As specified, US 266 had its eastern terminus at Warner, Oklahoma. From there, it ran westward for some 130 miles to Oklahoma City, where the route would end at a junction with its parent highway. Since US 266 as planned would exist only in Oklahoma, it was thus not a true “interstate” highway and consequently not considered a major thoroughfare. Nonetheless, the number and its proposed routing were submitted to the American Association of State Highway Officials (AASHO, now AASHTO), and approved in November 1926.
For part of its routing US 266 was multiplexed with US Highway 64, creating a more direct route for travelers heading from Fort Smith, Arkansas through to Oklahoma City. The route remained in place as originally laid out until AASHO made a number of changes to the federal highway plan in June 1931. Among those changes, US Highway 62 was extended through Oklahoma, intersecting US 266 at Henryetta (former home of Dallas Cowboys quarterback Troy Aikman). Instead of multiplexing the two routes, a decision was made to terminate US 266 at its junction with US 62, reducing the highway’s total mileage to what it is today, just a bit over 40 miles. With that change, US 266 became one of the shortest federal routes in the system. It is one of the two branches of 66 to survive to the present day (the other being US Highway 166).
Droz, Robert V., "Sequential List of US Highways", US Highways From US 1 to US 830. July 2003. <http://www.us-highways.com/us1830.htm> (February 2004)
Sanderson, Dale, "End of US Highway 266", US Highway Ends. January 2002. <http://www.geocities.com/Yosemite%2FFalls%2F3369/HwyEnds/End266/end266.htm> (February 2004)
Stuve, Eric, "US 266", OKHighways.com. 2003. <http://www.okhighways.com/us266.html> (February 2004)
Weingroff, Richard F., "U.S. 666: Beast of a Highway?", Federal Highway Administration Highway History
. June 2003. <http://www.fhwa.dot.gov/infrastructure/us666.htm> (March 2004)