Let's play a game...
https://nuclearwarmap.com
A couple different nuclear war simulations. The whole attack (1200 warheads) takes a minute or two to run for a simulated two hour attack.

Buckley SFB (near where I live) gets four or five nukes - I guess to make sure it gets plastered. That is more than Denver. But then Colorado Springs (home of Cheyanne Mountain) gets a LOT more including surface bursts.

The explanation mentions that a big attack in LA causes a deadly plume all the way to Phoenix.