Legislative and executive documents, many originating from the important period between 1789 and the beginning of the U.S. Congressional Serial Set in 1817 (See also U.S. Congressional Serial Set)
The Library of Congress's National Digital Library contains more than 100 collections, which feature historical photos, maps, documents, letters, speeches, recordings, videos, prints, etc.
This source is a digital publishing initiative of the University Library of the University of North Carolina at Chapel Hill. The texts and materials come mainly from the library's southern holdings.
NARA preserves historically valuable archives of the U.S. government, including documents, photographs, images, maps, audio clips, letters, speeches, and films.
A website on the impact of the Civil War on two counties, Franklin County in Pennsylvania and Augusta County in Virginia. Contains much primary source material.