It really focuses on the settlement of the American west after the Civil War, The Indian Wars, the large cattle drives, wild west towns and outlaws, etc. One of the things I liked most about it was that it contained a lot of pictures from the 19th century as well as several maps of the cattle trails, the battles between the US government and the Indian nations, etc. I highly recommend it.
You can find it on the History Rhymes Store (powered by Amazon.com) for $11.56.