LIBRARY OF CONGRESS:
Abraham Lincoln Papers – http://memory.loc.gov/ammem/alhtml/malhome.html
The Alfred Whital Stern Collection of Lincolniana – http://www.loc.gov/collection/alfred-whital-stern-lincolniana/about-this-collection/
Digital Collections – https://www.loc.gov/library/libarch-digital.html especially:
Making of America: University of Michigan – http://quod.lib.umich.edu/m/moagrp/
The "Making of America (MOA) is a digital library of primary sources in American social history primarily from the antebellum period through reconstruction...The book collection currently contains approximately 10,000 books with 19th century imprints."
The Collected Works of Abraham Lincoln – http://quod.lib.umich.edu/l/lincoln/
We have this in the library [E457.91 1953b v1-9] here it is – online and searchable.
Lincoln Research – https://www2.illinois.gov/alplm/library/lincoln/Pages/default.aspx
The Lincoln Archives Digital Project – http://www.lincolnarchives.us/
These digitized documents are housed at the National Archives. It includes political cartoons, photographs, newspapers, and other primary sources.
Lincoln/Net: Abraham Lincoln Historical Digitization Project – http://lincoln.lib.niu.edu/
“Lincoln/Net presents historical materials from Abraham Lincoln’s Illinois years (1830-1861), including Lincoln’s writings and speeches as well as other materials illuminating antebellum Illinois.” Essays, Maps, Videos, Music, etc.
Everything Lincoln – http://www.everythinglincoln.com/index.html
“Everything to do with Abraham Lincoln: biographies and articles, podcasts and educational materials, ephemera and pop culture. It's here!” A site created by a Lincoln fan, which includes a bibliography and explains her background.
Making of America: Cornell University – http://ebooks.library.cornell.edu/m/moa//
“The Cornell University Library Making of America Collection is a digital library of primary sources in American social history from the antebellum period through reconstruction…” A searchable version of the Official Records of the Union and Confederate Armies can be found on this site.
HARPWEEK.com - free access to Harpers Weekly (as compared to HARPWEEK through the library). Includes Political Prints and Cartoons.
Documenting the American South – http://docsouth.unc.edu/index.html
Documenting the American South (DocSouth) is a digital publishing initiative that provides Internet access to texts, images, and audio files related to southern history, literature, and culture. Currently DocSouth includes sixteen thematic collections of books, diaries, posters, artifacts, letters, oral history interviews, and songs.
Picturing U.S. History - http://picturinghistory.gc.cuny.edu/wwwvisualhistory.php
The site describes many different sites to obtain visual sources in digital form.