I came across this web page in the Caltrans site. It has links to detailed Caltrans maps that show the maintenance facilities of every district. Larger districts are split up into regions and the boundaries of those regions are shown. I had previously run across a few of these maps, but finding the comprehensive list is fortunate as my book had a lot of holes. It is now complete. I hope theses are of use to some people.
Right of Way Telecommunications (Wireless) Licensing Program
Right of Way Telecommunications (Wireless) Licensing Program