These mega-sites are good places to start your search for primary sources
American Antiquarian Society
An independent research library founded in 1812 in Worcester, Massachusetts. The library's collections document the life, culture and history of American people from the colonial era through the Civil War and Reconstruction (1876). Collections include books, pamphlets, newspapers, periodicals, broadsides, manuscripts, music, graphic arts, and local histories.
Internet Archive
Offers permanent access for researchers, historians, and scholars to historical collections that exist in digital format, including texts, audio, moving images, and software as well as archived web pages.
National Archives and Records Administration (NARA)
Established in 1934 by President Franklin Roosevelt to permanently preserve the nation's most important documents, NARA's major holdings date back to 1775. They capture the sweep of the past: slave ship manifests and the Emancipation Proclamation; captured German records and the Japanese surrender documents from World War II; journals of polar expeditions and photographs of Dust Bowl farmers; Indian treaties making transitory promises; and the Louisiana Purchase Treaty that doubled the territory of the young republic. NARA keeps only those Federal records that are judged to have continuing value—about 2 to 5 percent of those generated in any given year; however, this amounts to billions of pages of documentation.
Archives West
Provides access to archival and manuscript collections in Idaho, Montana, Oregon, Alaska, Utah and Washington through a union database of Encoded Archival Description (EAD) finding aids. Subjects include the major economic forces in the region- agriculture, forest, products, fisheries, and natural resources; urban and rural social and progressive movements; local state, regional, and national politics; outdoor recreation; Native American language and culture; and the place of religious communities in the region.
