Clearly, there is plenty to explore here, but the pic Slate republished is the one that caught my eye. It reflects travel times in the United States at various points in history – one week from New York City to North Carolina in 1800, for example – and numerous routes of travel. I really dig the panel on navigable rivers.
|"Rates of Travel, 1800-1930." Atlas of the Historical Geography of the United States, by Charles O. Paullin, ed. John K. Wright, published by the Carnegie Institution and the American Geographical Society, 1932. |
David Rumsey Map Collection.
A quick look shows David Rumsey has a lot of potential for inspiration and game use. Here's another awesome illustration of the Black Hills.