Archival Research Catalog (ARC) 
Online catalog of the National Archives and Records Administration's (NARA) nationwide holdings in the Washington DC area, Regional Archives, and Presidential Libraries.

Black Thought and Culture 
Full text of over 1,200 books, essays, articles, pamphlets, speeches, and previously unpublished material related to African American history from colonial times to the present.

Early American Imprints, Series I: Evans 1639-1800 
Digital collection of books, pamphlets, broadsides, and primary source material published in the United States between 1639-1800.

Eighteenth Century Collections Online 
Digital collection of books printed in the 18th century, primarily in Great Britain. Subjects covered include history, literature, religion, law, fine arts, science and more.

Gale Primary Sources

Provides a universal research experience that combines Gale's acclaimed digital archives in a single cross-search interface. By building a seamless research environment for multiple collections, Gale is creating the largest digital humanities and social sciences resource in the world.

Making of the Modern World 
Digital collection of economic and business literature published from 1450 to 1850, providing historical insight on the political, social, and economic conditions of the modern era.

National Union Catalog of Manuscript Collections 
Catalog of over 500,000 records describing archival and manuscript collections in research libraries, state and federal agencies, museums, and historical societies throughout the world.

Women and Social Movements 
Digital collection of articles, essays, books, bibliographies, and primary source materials documenting the history of women's reform activities in the U.S. from 1600 to 2000.

Library of Congress Digital Collections 
Digital collection of historical materials from the Library Congress. Includes a variety of manuscripts, pamphlets, images, audio and video recordings, maps, and sheet music that document U.S. history and culture.

Core Documents of U.S. Democracy 
Online access to "cornerstone" government documents such as the U.S. Constitution and Declaration of Independence and legal and judiciary documents.

Digital Public Library of America [DPLA]

The DPLA brings together the riches of America’s libraries, archives, and museums, and makes them freely available to the world.  It strives to contain the full breadth of human expression, from the written word, to works of art and culture, to records of America’s heritage, to the efforts and data of science.

EuroDocs 
Selected primary source documents related to key events in European history.

History Matters 
Designed for high school and college teachers and students of U.S. history survey courses, this site serves as a gateway to web resources and offers unique teaching materials, first-person primary documents, and guides to analyzing historical evidence.

Making of America 
Digital library of primary sources in American social history from the antebellum period through reconstruction. The collection is particularly strong in the subject areas of education, psychology, American history, sociology, religion, and science and technology. 

New York Public Library Digital Gallery 

Explore 839,576 items digitized from The New York Public Library's collections.  This site is a living database with new materials added every day, featuring prints, photographs, maps, manuscripts, streaming video, and more

New York State Digital Collections 
Digital collection of primary source materials held by the New York State Archives, State Library, and State Museum. Collections include photographs, textual materials, artifacts, government documents, manuscripts, and other materials.

New York State Historical Literature Collection 
Digitized collection of selected monographs, pamphlets and other materials from from the Cornell Library's extensive collection of New York State Literature.

Visualizing Injustice: Early NAACP Cartographers and Racial Inequality in America

An important moment in the use of the medium for this purpose, and in the history of cartography, came from a small group of Black intellectuals, who began to use spatially relevant demographic data to create maps, in order to visualize both the contributions of former slaves and African Americans to American culture, and also to highlight the persistence of racial injustice in the decades after emancipation. This blog from the Library of Congress highlights this.