Way back in 1932, Charles O. Paullin and John K. Wright published an Atlas of the Historical Geography of the United States. It was a seminal reference book, containing almost 700 fascinating maps—and now it's been digitized for you to explore online.

The thing is absolutely rammed full of fascinating data, mapped across the US—from weather, travel and population, to gold reserves, oil fields and vegetation types. It's been painstakingly transcribed t the digital format by the Digital Scholarship Lab at the University of Richmond. They explain:

In this digital edition we've tried to bring—hopefully unobtrusively and respectfully—Paullin and Wright's maps a bit closer to that ideal. First, with the exception of the historical maps from the cartography section and a handful of others (those that used polar projections, for example), we've georeferenced and georectified all of the maps from the atlas so that they can be overlaid consistently within a digital mapping environment. (Georeferencing is a process of linking points on a map to geographic coordinates, and georectification is a process of warping a map using those coordinates to properly align it within a particular projection, here web mercator.) High-quality scans of all of the maps as they appeared on the plates are available too.

The digital overhaul preserves all the original data, but also adds in subtle tooltips and animation, along with easily navigable mapping, to make the whole thing way more user friendly. You could spend (waste?) days looking through this thing. What are you waiting for? [Digital Scholarship Lab via Flowing Data]