Volume 4 of 4. Being an Outline of the Development in Modes of Travel from Archaic Vehicles of Colonial Times to the Completion of the First Transcontinental Railroad: the Influence of the Indians on the Free Movement and Territorial Unity of the White Race: the Part Played by Travel Methods in the Economic Conquest of the Continent: and those Related Human Experiences, Changing Social Conditions and Governmental Attitudes which Accompanied the Growth of a National Travel System.