Free Digital Libraries
The largest open-access (free) digital libraries are Google Books, the Hathi Trust Digital Library, and Europeana. Other major projects include the Library of Congress American Memory Project, Making of America (19th-century U.S. History), and the New York Public Library Digital Collections.
Hundreds of smaller, regional digital libraries exist. For lists of the most significant resources, see:
Newspapers and news broadcasts are excellent ways of experiencing and understanding history as it happened.
For an overview of available resources, see this database list: