Arizona using smaller towns/cities as control cities on interstates in the past

[MattHanson939]

A few years ago, I stumbled across old photos of Interstate highway signs in Arizona taken sometime before US 66 was decommissioned (so around the 70s or early 80s).  And they were overhead signs along I-40 in Flagstaff.  If I recall correctly, I noticed it signed for the next town just an hour away but was dual-signed with a faraway destination, unlike states such as New Mexico or Pennsylvania that only like to sign in-state control cities until you get closer to the state line.  And if not mistaken, those photos showed westbound I-40/US 66 dual-signed for Seligman and Los Angeles and eastbound was signed for Winslow and Albuquerque.  I also wonder if it was the case back in the day were I-8 west was dual signed for Yuma and San Diego.

I forgot what site I found those photos.