Northwest Digital Archives: Provides access to finding aids from historical repositories in the Pacific Northwest. 

Washington State Digital Archives: Digital full-text access to select public records, including birth, death, and census records.

National Union Catalog of Manuscript Collections (NUCMC): A database of catalog records for archival collections held by institutions throughout the United States. 

American Memory: A free, full text electronic archive of images, sounds and texts from 19th- and 20th- century America. 

Repositories of Primary Source: A directory of web sites for archives and manuscript repositories throughout the world.  An excellent place to find contact information for archives and archivists in any region you are studying.