Many libraries and archives around the world, both brick-and-mortar and online, house collections useful for genealogy. In the United States, these varied repositories include, but are not limited to, the following.


Allen County Public Library Genealogy Center (Fort Wayne, Indiana)
http://www.genealogycenter.org/

Clayton Library Center for Genealogical Research (Houston, Texas)
http://www2.houstonlibrary.org/clayton/

Denver Public Library (Denver, Colorado)
https://history.denverlibrary.org/genealogy

Digital Public Library of America
https://dp.la/

Family History Library (Salt Lake City, Utah)
https://familysearch.org/locations/saltlakecity-library

Google Books
https://books.google.com/

Hathi Trust Digital Library
https://www.hathitrust.org/digital_library

Internet Archive
https://archive.org/index.php

Library of Congress (Washington, DC)
https://www.loc.gov/

Mid-Continent Public Library Midwest Genealogy Center (Independence, Missouri)
http://www.mymcpl.org/genealogy

National Archives and Records Administration (Washington, DC, and regional branches)
https://www.archives.gov/

National Society Daughters of the American Revolution Library (Washington, DC)
http://www.dar.org/library

Newberry Library, Genealogy and Local History (Chicago, Illinois)
https://www.newberry.org/genealogy-and-local-history

New England Historic Genealogical Society Research Library (Boston, Massachusetts)
https://www.americanancestors.org/education/learning-resources/read/using-the-nehgs-library

New York Public Library, Research (New York City, New York)
https://www.nypl.org/about/divisions/milstein

St. Louis County Library, History & Genealogy (St. Louis, Missouri)
https://www.slcl.org/genealogy

Library of Virginia (Richmond, Virginia)
http://www.lva.virginia.gov/

Wisconsin Historical Society Library
https://www.wisconsinhistory.org