American Memory, Maps of the World, 1544-1996
http://oddens.geog.uu.nl/index.html

Best Map Collection: Oddens Bookmark
http://memory.loc.gov/ammem/gmdhtml/gmdhome.html

Broer Map Library
http://www.broermapsonline.org/members/

David Rumsey Historical Map Collection
http://www.davidrumsey.com/

The Hebrew University of Jerusalem: Historic Cities
http://historic-cities.huji.ac.il/

Historical Atlas of the Twentieth Century
http://users.erols.com/mwhite28/20centry.htm

Historical Maps Overview
http://www.culturalresources.com/Maps.html

Historic USGS Maps of New England and New York
http://docs.unh.edu/nhtopos/nhtopos.htm

Internet Medieval Sourcebook
http://www.fordham.edu/halsall/sbookmap.html

Sam Houston State University: The World Since 1914 Maps
http://www.shsu.edu/~his_ncp/369map.html

The Library of Congress American History Map Collections
http://memory.loc.gov/ammem/collections/civil_war_maps/

Library of Congress: American Reading Room
http://memory.loc.gov/ammem/browse/ListSome.php?category=Maps

The Library of Congress: Geography and Map Reading Room
http://www.loc.gov/rr/geogmap/

Mardos Memorial of Online Maps
http://www.memoriallibrary.com/

Perry Castaneda Library Map Collection
http://www.lib.utexas.edu/maps/historical/index.html

University of California Berkley Earth Sciences and Map Collection
http://library.berkeley.edu/EART/browse.html

University of Georgia Rare Map Collection
http://www.libs.uga.edu/darchive/hargrett/maps/maps.html

Worldview Antique Maps and Books
http://worldviewmaps.com/fresh/default.aspx