The study of the economic development of the Rio Grande Plain has been divided into the following seven chapters: (1) Physical Aspects of the Rio Grande Plain, (2) Grazing, (3) Development of Farming, (4) Development of Transportation, (5) Growth of Major Urban Centers, (6) Development of Natural Resources, and (7) Present Trends. In each chapter except Chapters I and VII, effort has been made to locate the origin of that particular industry and trace its development. In order to understand the development in the raising of livestock, farming, transportation, natural resources, and the growth of major cities of the region, it would be well to understand the physical aspects of the region.