Part 1; the history of US Route 191Y
What is now US Route 191Y and Page Ranch Road was added to the Arizona State Highway System during September 9, 1927, as Arizona State Route 81. Arizona State Route 81 originated at US Route 80 near Douglas and terminated at the US Route 180 in Safford. Arizona State Route 81 can be seen aligned past Bowie Junction and modern Page Ranch Road on the 1927 Arizona State Highway Commission Map.
Arizona State Route 81 was one of the original Arizona State Routes to be defined.
During the December 8, 1938, American Association of State Highway Officials (AASHO) meeting the Executive Commitee approved an Arizona Highway Commission request to extend US Route 666 to US Route 80. The extension of US Route 666 subsumed the entirety of Arizona State Route 81.
US Route 666 appears co-assigned with Arizona State Route 81 on the corridor of Page Ranch Road towards Bowie Junction on the 1939 Rand McNally Map of Arizona.
One of the earliest highway maps to display Page Ranch Road split from US Route 666 is the 1948 Rand McNally Map of Arizona. Page Ranch Road is displayed as a locally maintained roadway connecting from Arizona State Route 86 at Bowie Junction northwest to US Route 666.
On May 8, 1992, the Arizona Department of Transportation submitted an application to AASHTO eliminate US Route 666 in the state. The application came with a secondary request to extend US Route 191 from Chambers south to the Mexican border in Douglas over the existing routing of US Route 666. Both requests were approved by the AASHTO Executive Committee on June 15, 1992.