What is the theme in House of Sand and Fog by Andre Dubus III?

The American dream is another theme of the story. Kathy Nicolo's father, a man born of an Italian immigrant family, ran a linen business on the east coast of the U.S. He left Kathy and Frank a house in on its west coast. Kathy and her new husband Nick travel west in their Bonneville (as an interesting sidenote, a Captain James Bonneville was used by one of the first explorers of the U.S. Rocky Mountain West). Kathy and Nick migrate to their new west coast home, making the crossing in a one-week nonstop trip. Kathy's memory of the trip is somewhat blurred-for example, when she imagines that the car was on cruise-control the entire trip (cars, of course, kick out of cruise-or burn up their motors-going up steep hills, like the Rocky Mountains).