All parts of Volumes 1, 2, and 3 are accessible online at no cost.
http://www.press.uchicago.edu/books/HOC

The University of Chicago Press publishes The History of Cartography in print, e-book, and online formats. Currently, Volume 1, Volume 2 (Books 1, 2, and 3), and Volume 3 are available to the public online. All content–text, footnotes, images and captions, bibliographical index, and general index–may be accessed at no cost through downloadable and searchable PDF files. The remaining volumes will be similarly available within three years of print publication.

More than 2.5 million individual chapters of the History had been downloaded by December 2016.