A great book for the roads in the area, and best if you buy it beforehand for planning your trip, rather than buying it in a gift shop. It is divided up into sections of the major highways, and is easy to follow. The bits of historical information are interesting, and it will lead you to things you might not otherwise take a look at (or know to look for), including geological formations along the road. It also shows where services are available, including gas -- and in that big open country, that's a nice thing to know. The only downside is that it hasn't been updated since the mid-90's, but the only real changes are a few of the prices and hours of operation, along with the addition of a few hotels and amenities. Overall, a fantastic guide.