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/
> The Greater Phoenix area casts a nighttime arc of light over most of Arizona, extending more than 200 miles in each direction.
Former astronomer here. From Mt. Graham in Arizona you can see the sky glow from Los Angeles. Phoenix is a lot closer than that.
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.