During the 1850s, the U.S. government sponsored an extensive series of expeditions designed to gather information on the vast new territories that had been acquired in western North America. The discovery of gold in California further stimulated westward traffic and heightened the need for a faster and more convenient way to bring the far-flung parts of the country together. In 1853 Congress commissioned the Army's Topographic Bureau to conduct a series of surveys to find a suitable route for a transcontinental railroad. There were six major expeditions; five of them covered the area between the Great Plains and west coast, and the sixth explored the coastal states of California and Oregon. All of these expeditions were accompanied by naturalists and artists to document the landscape, flora and fauna along the route. The reports, maps and lithographs were published in the 13 volume report "Explorations and Surveys to ascertain the most practicable and economical route for a Railroad from the Mississippi river to the Pacific Ocean."

Gunnison's final and most detailed map of the series that Wheat illustrated in full. Minimal detail in the north and south, the map provides much detail along the route through western Colorado and Utah. Locates Fort Uintah, Brown's Hole, the Old Spanish Trail, and Bridger's Pass. An interesting and important map of the region that would eventually be followed by the Denver and Rio Grande Railroad. Capt. Gunnison was killed by hostile Indians at the western portion of this exploration, but Beckwith recovered his survey notes and completed the map.

References: Wagner & Camp #266C; Wheat (TMW) #846.

Condition: B

Issued folding, now tissue backed. Toned along folds.