The first large-scale purchase of vehicles for letter carriers included an odd looking three-wheeled, lightweight conveyance known as a “mailster.” The mailster worked best in temperate climates or on even terrain. In other areas, they sometimes did not work at all. Northern carriers, immobilized in as little as three inches of snow, also complained of the vehicles’ inability to heat properly. The three-wheel design left mailsters susceptible to tipping over if cornering over 25 miles per hour or if caught in a wind gust. One carrier complained that his mailster was tipped over by a large dog.