Came across photos that I had in my files of Maricopa Road east of AZ 85 in Sonoran Desert National Monument. If I recall correctly the current AZ 85 meets Maricopa Road on an interchange built circa 2011-2012 which was signed as "To AZ 238." I never could track down what the numbering convention between AZ 238 and AZ 347 was, the former still oddly ends just west of Mobile:
https://surewhynotnow.blogspot.com/2018/10/national-park-wednesday-maricopa-road.html
SR 347 was derived from the FHWA secondary route number when it was a two-lane road from Maricopa to the Chandler area.
Quote from: Zonie on October 26, 2018, 12:23:59 PM
SR 347 was derived from the FHWA secondary route number when it was a two-lane road from Maricopa to the Chandler area.
No kidding, at least it comes from somewhere. It's too bad Arizona couldn't stick to its original numbering convention or at least update for the Interstate era. The new route numbers coming out feel out of place IMO.