The University of Richmond has digitized the Atlas of the Historical Geography of the United States, the 1932 masterpiece from Charles O. Paullin and John K. Wright. You can just flip through the hundreds of maps, but the real treat is seeing the maps all made the same size and placed on a modern map of the country.
A lot of Nashville's history is tucked into these maps—from our place on the old post roads in 1804 to how well-connected we were to the rest of the country by railroad in 1870. I was most curious about the "Canals and Canalized Rivers, 1930" map. I'd like to know more about how the Cumberland was kept navigable before the rise of the TVA. But there are other cool things to wonder about in there, like who was doing cotton farming around here and why they stopped.
Anyway, it's a nice way to burn an afternoon.