Skip to main content

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

Popular posts from this blog

Did Caltrans just kill the G26 cutout US Route shields?

The US Route System was formally created by the American Association of State Highway Officials during November 1926.  Through the history of the system the only state to which has elected to maintain cutout US Route shields has been California.  The G26 series cutout US Route shields have become a favorite in the road enthusiast hobby and are generally considered to be much more visually pleasing than the standard Federal Highway Administration variant.  However, the G26 shield series appears to have been killed off on January 18, 2026, when Caltrans updated their Manual of Uniform Traffic Control Devices.  This blog will examine the history of the US Route shield specifications in California and what is happening with the 2026 changes.  The blog cover photo is facing towards the terminus of California State Route 136 and at a G26-2 specification US Route 395 shield.  In the background Mount Whitney can be seen in the Sierra Nevada range.   ...

Trans-Sierra Highway Passes; Interstate 80 Donner Summit

Back in 2016 I attempted as many Trans-Sierra Highway Passes as I could upon my return to California.  I started with Interstate 80 over Donner Summit during the late winter on the way to Lake Tahoe and Virginia City. Donner Summit is actually located north of the 7,056 foot Donner Pass.  Donner Summit has a listed height of 7,277 feet above sea level which is listed at the rest area on the eastbound lanes heading towards Truckee. As I-80 begins to descend from Donner Summit there is an overlook of Donner Lake and Donner Pass. US 40, the Lincoln Highway, First Trans-Continental Railroad, and the Dutch Flat & Donner Lake Railroad all crossed Donner Pass on various different alignments to the south of Donner Summit. Previously I wrote a blog about Donner Pass which includes a history of early pioneer crossings, the Donner Party, the Dutch Flat & and Donner Road, the Lincoln Highway, and of course US 40 which can be found here: Old US Route 40 on Don...

May 2023 Ontario Trip (Part 3 of 3)

  Over the years, I have made plenty of trips to Ontario, crisscrossing the southern, central and eastern parts of the province. Living in Upstate New York, it's pretty easy to visit our neighbor to the north, or is that our neighbor to the west? Ottawa is one of my favorite cities to visit anywhere in the world, plus I've discovered the charm of Kingston, the waterfalls of Hamilton (which is on the same Niagara Escarpment that brings us Niagara Falls), the sheer beauty of the Bruce Peninsula, and more. But I hadn't explored much of Cottage Country. So I decided to change that, and what better time to go than over Memorial Day weekend, when the daylight is long and I have an extra day to explore. On the third and final day of my trip, I started in Huntsville and made my way through Muskoka District and Haliburton County, passing by many lakes along the way. I stopped in towns such as Dorset, Haliburton and Bancroft before making a beeline down to Belleville and then over th...