It’s a real shame that Phoenix metro is going to ruin everything for Flagstaff and Tucson in the not-too-distant future by refusing to implement any light limits at all.
Dark skies require a pretty high radius of dark landmass. For an estimate of the extent of this, try seeing the areas around major cities here: https://www.lightpollutionmap.info/
I live in Dallas-Fort Worth and grew up near Amarillo, TX. In high school I regularly drove a few miles (like less than 5) away from the city to look at lights. I've noticed in DFW you've got to get much much further away from the city. I can't really put a number on it, but I know even 20 miles out of town you can still only see the brightest stars.
