Arizona State Route 366 and Mount Graham

The photo below was taken back in 2012 from US Route 70 near Safford looking south towards the 10,724 foot Mount Graham near Safford in Graham County. Mount Graham is the location of one of the few Arizona State Routes I never fully finished; AZ 366.

Arizona State Route 366 is a 28.33 mile state highway running west from US 191 in Swift Trail Junction to the Columbine Ranger Station of Coronado National Forest. While AZ 366 doesn't technically go all the way to the summit of Mount Graham it does provide access to it via connecting National Forest Routes. Approximately the first 22 western most miles of AZ 366 are paved while the remaining portion of the route is gravel.

AZ 366 was established as a State Highway in 1960. The numbering convention of "366" comes from the connection the route had with US 666 which was eventually renumbered in Arizona to US 191. Prior to the Interstates being built all Arizona State Routes had a number that was consecutive of a US Route. Initially the routing of AZ 366 was reportedly only about 6 miles west from US 666 Swift Trail Junction but was quickly expanded to the modern 28.33 miles. This 1961 Arizona State Highway Map shows the full routing of AZ 366 much as it appears today.

1961 State Highway Map

AZ 366 appears to be not much more than a maintenance swap between ADOT and Coronado National Forest. The eventual routing of AZ 366 appears as "Swift Trail" on the 1956 Arizona State Highway Map.

1956 State Highway Map

The summit of Mount Graham is the location of the Mount Graham International Observatory which began operations in 1993. Mount Graham is one of five Ultra-prominent peaks in Arizona which have prominence of over 5,000 feet above the surrounding terrain. Mount Graham ranks 50th overall in the United States in terms of prominence at 6,340 feet above the surrounding terrain.

Comments

Interstate 40's Tumultuous Ride Through the Pigeon River Gorge

In the nearly 60 years Interstate 40 has been open to traffic through the Pigeon River Gorge in the mountains of Western North Carolina, it has been troubled by frequent rockslides and damaging flooding, which has seen the over 30-mile stretch through North Carolina and Tennessee closed for months at a time. Most recently, excessive rainfall from Hurricane Helene in September 2024 saw sections of Interstate 40 wash away into a raging Pigeon River. While the physical troubles of Interstate 40 are well known, how I-40 came to be through the area is a tale of its own. Interstate 40 West through Haywood County near mile marker 10. I-40's route through the Pigeon River Gorge dates to local political squabbles in the 1940s and a state highway law written in 1921. A small note appeared in the July 28, 1945, Asheville Times. It read that the North Carolina State Highway Commission had authorized a feasibility study of a "...water-level road down [the] Pigeon River to the Tennessee l

Mines Road

Mines Road is an approximately twenty-eight-mile highway located in the rural parts of the Diablo Range east of the San Francisco Bay Area. Mines Road begins in San Antonio Valley in Santa Clara County and terminates at Tesla Road near Livermore of Alameda County. The highway essentially is a modern overlay of the 1840s Mexican haul trail up Arroyo Mocho known as La Vereda del Monte. The modern corridor of Mines Road took shape in the early twentieth century following development of San Antonio Valley amid a magnesite mining boom. Part 1; the history of Mines Road Modern Mines Road partially overlays the historic corridor used by La Vereda del Monte (Mountain Trail). La Vereda del Monte was part of a remote overland route through the Diablo Range primarily used to drive cattle from Alta California to Sonora. The trail was most heavily used during the latter days of Alta California during the 1840s. La Vereda del Monte originated at Point of Timber between modern day Byron and Bre

Interstate 210 the Foothill Freeway

The combined Interstate 210/California State Route 210 corridor of the Foothill Freeway is approximately 85.31-miles. The Interstate 210/California State Route 210 corridor begins at Interstate 5 at the northern outskirts of Los Angeles and travels east to Interstate 10 in Redlands of San Bernardino County. Interstate 210 is presently signed on the 44.9-mile segment of the Foothill Freeway between Interstate 5 and California State Route 57. California State Route 210 makes up the remaining 40.41 miles of the Foothill Freeway east to Interstate 10. Interstate 210 is still classified by the Federal Highway Administration as existing on what is now signed as California State Route 57 from San Dimas south to Interstate 10. The focus of this blog will mostly be on the history of Interstate 210 segment of the Foothill Freeway. Part 1; the history of Interstate 210 and California State Route 210 Interstate 210 (I-210) was approved as a chargeable Interstate during September of

Gribblenation

Search This Blog