Searchable database includes scanned PDFs of the ballot proposition information booklets from 1911-present, but no information about the final status of the propositions.
1912 to the present, includes summary of results and statistical data such as percentage votes. Also covers proposed initiatives that did not qualify for the ballot.
Starts with 1995/96 and is usually a couple of years out of date. Reports from election officials to the Secretary of State containing information regarding citizen-generated initiative measures.