While today you might have to study Twitter, Facebook or peoples IP addresses to determine where they live and travel, this visualization of westward expansion in the US between 1700 and 1900 looks at the most popular social network of the day: the post office. To create the graphic, map obsessed Derek Watkins took data from the USPS Postmaster Finder and found latitude/longitude coordinates extracted from place names checked with the USGS. [Read more...]