CartoMundi offers about 35 000 references of cartographic documents. They cover 185 countries and are hold in about 20 different map libraries.
British Museum Maps Collection
The British Library has a Georeferencing Project which features over 3,000 more maps from the British Library collections.
Library of Congress Map Collection
The Library of Congress has custody of the largest and most comprehensive cartographic collection in the world. The online map collections represents only a small fraction that have been converted to digital form.
Database of proprietary, royalty-free world, continent, country, and state maps. Included in the 4,000+ maps are: political maps, physical maps, outline maps, population maps, precipitation maps, climate maps, and other thematic maps. New maps are added to the collection every month.
The USGS is a science organization that provides impartial information on the health of our ecosystems and environment, the natural hazards that threaten us, the natural resources we rely on, the impacts of climate and land-use change, and the core science systems that help us provide timely, relevant, and useable information.
The GEOnet Names Server (GNS) is the official repository of standard spellings of all foreign geographic names, sanctioned by the United States Board on Geographic Names (US BGN). The database also contains variant spellings (cross-references), which are useful for finding purposes, as well as non-Roman script spellings of many of these names