US route endpoint in
Tuba City, AZ

1965-present

In the early 1960s Arizona finished paving a new highway serving the Navajo Nation and the Hopi Tribe in the northeastern part of the state.  The road continued through the northwesternmost corner of New Mexico and then into Colorado, so these states petitioned AASHO to give it a US route number.  In 1965 AASHO approved the US 164[ii] designation for this highway.  Its west terminus was initially described as Flagstaff, but very shortly thereafter Arizona decided to have the route terminate at its junction with US 89 just west of Tuba City, so US 164 was never signposted between Tuba City and Flagstaff.  ​But just a few years later, in 1970 the US 160 designation was truncated at Cortez CO, and instead extended southwest, completely absorbing US 164 and ending at the same highway junction:

These photos show the west beginning of US 160 (and former west beginning of US 164) as viewed from both northbound and southbound US 89, respectively:

Research and/or image credits: Andy Field; Dale Sanderson; Shayne Stephens