Correct on all counts! Route 666 originated as an innocent spur off old Route 66, but that number, 666 has a sinister connotation, being the "number of the beast" as specified in the Book of Revelations. People took to calling it "The Devil's Highway," and some folks were nervous about driving on it.
Other folks thought it was cool, so much so that they took to stealing these highway signs as souvenirs:
Between the superstition and the persistent vandalism, the highway department was faced with a never-ending headache, so they simply changed the number of the road to US 191. The Coronado Trail Scenic Byway is that portion of US 191 that runs between Alpine and Morenci through the Blue River Wilderness and the rugged mountains of Eastern Arizona, right along the border with New Mexico. It's one of the twistiest and least traveled of all the U.S. Highways, reputed to have at least 460 switchbacks in 120 miles. Now that's my kind of road!
I thought somebody might pick up on the road sign with the quote from Aldo Leopold and the word "Blue," which leads pretty directly to the Blue River Wilderness. And the other sign I put up, the one with all the "XXX's"? The River and the Campground were faked, but the XXX Ranch is a real place, a rather famous ranch on the Blue River.
Either of those would have been easy to find in a search, but I never even stopped to think that the dad-burned arrow tree would be such a giveaway! With all-knowing, all-seeing Google spying on everything, there's no longer any such thing as a secret roadside attraction!
Rick