HeritageQuest offers the complete set of U.S. Census records, 1790-1940, plus over 25,000 family and local histories, and genealogical data, available courtesy of the Boston Public Library using the BPL eCard - get an eCard
There are many online exhibits of digitized archival resources. Use this tool from the Smithsonian Libraries to browse some!
Primary sources are original, uninterpreted information, such as firsthand accounts of events in letters, diaries, interviews, or historical news reportage; original works of fiction, art, or music; research data; testimony, speeches, etc. Visit Special Collections to use some original texts in print or manuscript.
Questions? Don't know where to start? Want advice on research strategies? I'm happy to meet with you -- see contact info at right!
The American Historical Association has put together this page on finding and evaluating archival resources that can be a good start for your search!