The Evergreen Highway

Once upon a time, highways had names, not numbers.  And so it was The Evergreen Highway was one of many such named routes that snaked their way across America and Arizona.  The Evergreen Highway predated US 89 and used a different route to get from Phoenix to Prescott.  Ironically, The Evergreen Highway closely followed what is today's I-17.  The map from which the screen clips are taken is dated 1924.  However, the map doesn't show The White Spar highway which was built in 1923.  Therefore, we'd suspect the map data (if you can call it data) used for this map is circa 1921-22.

Official US signage and numbering came about
for many reasons. One such reason was
that each named highway had its own logo.

Luckily, we were able to find some "core" information about The Evergreen Highway on Pages 176-177 of an April 1920 edition of  "The Rotarian."  Hopefully, this link will get you right to the article:  https://goo.gl/CpBxA6

Here is an excerpt from the Rotarian article: "The policy of The Evergreen Highway Association is not to construct an Evergreen Highway where no highway was before, but to use the different motor roads already built, have them connected with equally good roads so that there will be one continuous chain of open- roadway - communication between North, South, East and West during three hundred and sixty-five days of the year.  No roads already established are to change their names, but all are to be a part of the Evergreen Highway."

Full map of southwest is located here: https://goo.gl/YAANHP

The Evergreen Highway followed the route of what would become US 80 from El Paso to Phoenix.  At that point, The Evergreen Highway turned almost due north to Humboldt before turning west to enter Prescott.  From Prescott, the Evergreen Highway traveled north to Ash Fork and then followed what would become Rt. 66 to Needles and on to Las Vegas.

It would be only a few short years before all of the named highways became official US numbered routes, using a single sign design throughout the Nation. The completion in 1923 of the White Spar highway routed US 89 far to the West from the old Evergreen Highway.  Since the Evergreen Highway was largely a contrived route promoted by outsiders, the name quickly fell into disuse and is largely unknown today.