David Rumsey Map Collection
Enormous collection of maps available in high-resolution scans. Started over 30 years ago and containing more than 150,000 maps, the collection focuses on rare 16th through 21st century maps of North and South America, as well as maps of the World, Asia, Africa, Europe, and Oceania. The collection includes atlases, wall maps, globes, school geographies, pocket maps, books of exploration, maritime charts, and a variety of cartographic materials including pocket, wall, children's, and manuscript maps. Items range in date from about 1550 to the present.
Library of Congress Map Collection
Over 50,000 digital maps (and information about 375,000 more physical maps) searchable by time period, geography, subject, and more.
New York Public Library Maps and Atlases Collection
Browsable by geography.
Old Maps Online
This project began as a collaboration between Klokan Technologies GmbH, Switzerland and The Great Britain Historical GIS Project based at the University of Portsmouth, UK thanks to funding from JISC, now managed by volunteers. Indexes more than 400,000 maps.
Historic Map Works
Similar to Old Maps Online above, searchable by geography and era.
University of Texas Libraries' Map Collection
More than 14,000 current and historical maps from around the world arranged by geographic location, including older edition CIA maps.
A Google search for old maps and a location may yield additional resources, too.
Note that some of the historical collections above also include modern maps.
List of national mapping agencies
These are equivalents to the United States Geological Survey, but for countries around the world. Don't knock Wikipedia for some things!
United Nations list of general maps
Includes world, continent, region, country, and area maps.
National Map Downloader
A service of the USGS, providing access to downloads of topographic maps, boundaries, hydrographic information, transportation,
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