It's a state with a desert town large enough to support a professional sports franchise, that has exploded in population in recent decades due to transplants moving into a new suburban ring. That to me is Sunbelt.
My Sunbelt has the following states:
CA, NV, UT, AZ, CO, NM, TX, LA, MS, AL, GA, FL, GA, SC, NC
Though UT, CO, NC, and NoCal are "Fringe Sunbelt."
The main reason UT shouldn't be considered a sunbelt state is because its growth is based off of a high birth rate, rather than migration.
I find it shocking that Arizona will have more votes than Washington... that's just sad.