Institutional Map Collections with Extensive Digital Images
David Rumsey Map Collection, the gold standard of map imaging, more than 75,000 maps on line with metadata, GIS tools, etc.
Leventhal Map Center at the Boston Public Library.
Osher Map Library, Smith Center for Cartographic Education
Other Useful Links
Map History, the invaluable, comprehensive "gateway" site of Tony Campbell (former Map Librarian of the British Library)
The History of Cartography, the definitive multi-volume project; the first three volumes (5,000 pages!) on line, free
Mapping the Nation, Susan Schulten, focusing on American maps in the 19th century, a time when persuasive cartography was greatly expanding:
Strange Maps, hundreds of "cartographic curiosities," many of which involve persuasive cartograpy
Three Map Dealers, each with an eye for persuasive maps and a large online archive of images and well-researched descriptions: