Journalist Devin Leonard tackles the fascinating, centuries-long history of the USPS, from the first letter carriers through Benjamin Franklin’s days, when postmasters worked out of their homes and post roads cut new paths through the wilderness. Under Andrew Jackson, the post office was molded into a vast patronage machine, and by the 1870s, over 70% of federal employees were postal workers. As the country boomed, USPS aggressively developed new technology --- from mobile post offices on railroads and air mail service to mechanical sorting machines and optical character readers.