As of 2015, a good location to find state maps of California is the Geology site at Geology.com. The site offers detailed maps of the entire state, as well as city maps.
The Geology site includes highway maps and maps of the major river systems in the state. The physical maps showcase the major geological features of the state.
Another good site for maps of California is MapQuest. The site (MapQuest.com) offers maps and satellite pictures of the state. Directions can also be obtained along with traffic updates. MapQuest offers a free app for users to utilize when on the go. The site is free to use.