Car Electronics And Audio

What happened to the radio signal when someone drives to another state or major city?

SCENARIO: Mariella was driving from Flagstaff, Arizona to Las Vegas, Nevada listening to her favorite radio station. As she reached Hoover Dam, the radio tuned out on her and Mariella was hearing nothing, but static. What do you think happened?
Sorry, question mistake, I meant to say:

The radio signals were too weak to connect to the car's antenna and that's why the radio had static sounds. Mariella probably heard static BEFORE reaching the Hoover Dam as well because she has to pass lots of hills and mountains before reaching Hoover Dam and that will cut off the signal temporarily in Arizona when reaching those physical features. As Mariella was getting further away from the main radio station, the signals were getting weaker and weaker.

Alesha - Radio [OFFICIAL VIDEO] - OUT NOW