What happened to US 666?
On June 2, 2003, the Special Committee on U.S. Route Numbering ( http://cms.transportation.org/?siteid=68 ) within the Standing Committee on Highways ( http://highways.transportation.org/community/highways/site.nsf/homepage/overview/ ) of AASHTO (see 4.2) voted in the 2003 Spring Meeting to change the number of the remaining section of US 666 to US 491. Some say that this was influenced by “666” being interpreted by some as “the Number of the Beast” or the number representing the devil; others contend that the change came about due to the frequent theft of route markers (partly due to the “Beast” connotations) or to the long-time absence of US 666’s parent route, US 66 (see 7.4.1). The unused numbers 291 and 391 were not chosen for this renumbering since one or more of the states along the route (CO, NM, UT) has a state highway with the same number. The number 393 was briefly proposed before 491 was chosen. For US 666 history, including this numbering change and a reference to the “Num
