While the road is technically not considered a state highway within national park boundaries, as it is maintained there by the National Park Service and not the Arizona Department of Transportation, it is marked as SR 64 on most maps and is considered unbroken for the purposes of numbering in the Arizona state highway system.

SR 64 formerly extended past Cameron through to Teec Nos Pos; this designation has been superseded by US 160.

SR 64 was first designated as a state highway in 1932 as a route from Williams to the Grand Canyon.

[3] In 1961, the highway was extended further east from US 89 through Tuba City to the New Mexico state line.

State Route 64 Spur (SR 64 Spur) was an unsigned 0.36-mile (0.58 km) long auxiliary route of SR 64, connecting its parent highway to Grand Canyon National Park Airport.