Whats with the new US routes?
A handful of new US routes have been created recently. Some of these are out of the original numbering system and appear to use a new numbering system based on a multiple of 12.5 (in other words 437 may be next). US 412 is a NHS/ISTEA High Priority Corridor, and was designated in 1982 (see http://www.aaroads.com/high-priority/corr08.html ). It might become a future Interstate. US 425 was added to the US route system in 1989; this is the preferred corridor for any future extension of I-530 to I-69. Part of US 425 is included in the I-69 corridor (see 6.4 ). US 371 was added as a branch route of US 71 in 1995 in LA and AR. US 400 is also a NHS/ISTEA High Priority Corridor, added to the US system in 1996, the newest US route (see http://www.aaroads.com/high-priority/corr03.html ). The number was picked by Kansas DOT out of a list of available numbers, and agreed to by Missouri and Colorado. US 400 is also planned as a future extension of I-66. The third iteration of US 48 has recently app
