Internet Public Library - www.ipl.org 
Access materials for different subjects.
Library of Congress - www.loc.gov/index.html
This library is a must for students researching not only American History but now also International Affairs and Congressional history. This site links one to THOMAS - the legislative site, American Memory - wonderful primary reflections in American history, as well as museum feature exhibits.
NARA - Presidential Libraries - www.archives.gov/presidential-libraries/contact/libraries.html
National Archives and Records Administration has information and links to each presidential library and museum. On-line primary sources available in most presidential libraries.
New York Public Library - www.nypl.org
Some of the research collections are the best in the country - a unique collections is the Schomburg Collection on African Experience.
University of Texas - www.lib.utexas.edu/help/librarylist.html
The third largest library - this library is a tremendous site for multi use, including historical maps, news and newspapers from around the world, national and international government information, current, historical and primary sources.
Yale University - www.cis.yale.edu/ycias/research.htm
This library is valuable for social studies, IB, law, environmental studies, and statistics.
Global Directory of Library Home Pages - lists.webjunction.org/libweb
Click on to a university library site and then click to the on-line reference link-these are the best academic sites on the web. Special and public libraries as well.