ETS2/ATS Local Radio plays radio from where you are, in ATS. Every city broadcasts a set of radio stations, and you will only be able to play stations from the cities near you. That means Las Vegas radio around Las Vegas, and Eureka radio around Eureka. It will switch automatically, and allow you to switch stations while driving. You can easily switch radio stations, but because you probably don’t want to constantly alt+tab out of your game, you can also control the radio with another device (like your phone), controller or keyboard.
Please read the readme, as the installation differs from most mods.