The Pacific Railway surveys were undertaken at the direction of Congress to determine the best route for the first transcontinental railway. Army expeditions led by the Corps of Topographical Engineers and staffed with natural scientists, artists, and collectors began the surveys in 1853. Exploring parties moved along the four most popular proposed routes, ranging from the northernmost line, running from St. paul to Puget Sound, to the southermost, running through Texas and the Gadsden Purchase to San Diego. The reports from these expeditions funneled back to the Office of Pacific Railroad Explorations and Surveys in Washington, which compiled and evaluated data on the various factors affecting railway construction--geology, topography, and the availability of natural resources such as water, timber, stone, and coal. In 1855 the expeditions were complete. Each team's field reports, including narrative descriptions, hundred of maps, and thousands of illustrations, were organized along with the Survey Office's assessments into a massive 8,500-page series and presented to Congress. The reports of explorations and surveys, originally published in the Congressional serial set, is one of the great documents on nineteenth-century scientific endeavor and the exploration of the West. Its impact on American science was pervasive and enduring. The work of the topographical engineers at last enabled the creation of a map documenting the basic contours of the vast American West. Naturalists, geologists, and mineralogists brought back specimens and illustrations of a vast array of new organisms and phenomena. Encounters between surveying teams and then little-known Indian tribes resulted in some of the first ethnological records of these peoples. In addition to the surveys' value to historians of science, they are prime examples of the interaction between federal politics and science in the nineteenth century, demonstrating the government's determination to harness science in the service of national expansion, defense, and economic growth. As the historian William H. Goetzman writes: "The Pacific Railways surveys were an American encyclopedia of western experience. They included an immense amount of knowledge, took note of countless phenomena, and brought back specimens that made the Smithsonian one of the world's great museums. They represented, on an elevated level, the enthusiasm of an age which was just opening out onto the world and its natural mysteries, one in which every known phenomenon was being collected so that civilization could digest and account for them all." (p. 336).