Can you add music to 18 wheels of steel American long haul?

Yes. But you have to download the music from the internet on to the game. To find links to music for 18 WOS: ALH go to a search engine (google, Bing, AOL) and type in "Music Downloads for 18 Wheels of Steel: American Long Haul." Or "Music Mods for 18 Wheels of Steel: American Long Haul."