Among the growing body of scholarly publications that have been digitized for electronic consumption is the University of California Press E-Books Collection, 1982-2004.
Maintained in collaboration with the California Digital Library, the Collection contains almost 2,000 electronic editions of academic titles published by UC Press. All the e-books are freely available to UC faculty, staff, and students. And the public may view more than 25 percent of the online books for free.
The Collection is easily browsed by author, title and/or subject via the search interface. There are over 500 books in the field of history. Among the 68 volumes related to California that might interest you:
Contested Eden: California before the Gold Rush (1998)
Taming the elephant: politics, government, and law in pioneer California (2003)
A golden state: mining and economic development in gold rush California (1999)
California progressivism revisited (1994)
Days of gold: the California Gold Rush and the American nation (1997)
Gold: the California story (2000)
Railroad crossing: Californians and the railroad, 1850-1910 (1994)
Working people of California (1995)
Willie Brown: a biography (1996)
Battling the inland sea: American political culture, public policy, and the Sacramento Valley, 1850-1986 (1998)
Sierra crossing: first roads to California (1998)