By 1848 the United States had acquired official title to the contiguous land stretching westward to the Pacific, south to the Rio Grande, and north to the 49th parallel. Americans had long since explored and settled in many of these areas, but legitimate possession created impetus for development that began to crystallize as other timely occurrences brought a greater influx of people to the West. The religious persecution of the Mormons had led them to begin their migration westward by this time. The discovery of gold would soon draw thousands more across the country. The opportunity to start a new life and own land motivated many to head West.

This transition from a "wild" western frontier into organized segments of a federal union is documented in photographs. Private citizens and Government officials took the recently developed camera on their western adventures to record nature's curious sights and the marks that they as men and women made on the landscape. It is indeed a wonder that so many photographs have survived the hardships of the western experience, for early negatives were made of large glass plates. Some of these photographs have found their way into the National Archives as record materials of several Federal bureaus and offices, such as the Bureaus of Land Management, Indian Affairs, Public Roads, Weather, Agricultural Economics, and Reclamation; the Fish and Wildlife Service, the Geological Survey, boundary and claims commissions and arbitrations, the Corps of Engineers, the Forest Service, and the Signal Corps. The photograph above was selected from the records of these agencies now on deposit in the National Archives.

While the records of Federal agencies continue to document changes on the face of western America and the efforts toward effecting some kind of progress, an arbitrary cutoff date of 1912 has been used. At that time Arizona, the last of the contiguous 48 United States, was admitted to the Union. Having arrived at its destiny, the "Wild" West was in a sense officially terminated.