The Online Archive of California a.k.a. a Researcher's Best Friend
When I was designing my dissertation a friend in the area of library science shared with me an incredible resource: The Online Archive of California. The OAC is a repository for over 20,000 finding aids for the archival collections held by over 200 institutions throughout the state. Here you can identify the location of the collection, what it contains, how to access it, and if any of the materials are available online. The diversity of available materials is breathtaking.
This is the place I discovered the archives of the Webster Commission which became the focus of my dissertation. Even for researchers who don’t end up working with a collection in California, the OAC can be a great resource for stimulating ideas about what types of documents or artifacts one might look for in other locations.