If you run an image search for the word “ARPANET,” you will find lots of maps showing how the government research network expanded steadily across the country throughout the late ’60s and early ’70s. I’m guessing that most people reading or hearing about the ARPANET for the first time encounter one of these maps. Obviously, the maps are interesting—it’s hard to believe that there were once so few networked computers that their locations could all be conveyed with what is really pretty lo-fi cart...