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."

Wheat dedicates more than a full page to what he calls "a map of the greatest interest, not only for its route, which is that of the Southern Pacific Coast Line, but because of its showing of ranchos and missions along the route." The proposed line is shown from San Jose south to the Pubela de Los Angeles, San Bernardino and through the San Gorgonio Pass on its way east. Remarkable detail along the route including well rendered hachure depicting elevation. The Spanish Trail, mail route to Salt Lake City and Whipple's route are shown passing through Cajon Pass and on to the Mojave River.

References: Wheat (TMW) #852.

Condition: B+

Issued folding, with light toning along a few fold lines. Professionally backed in tissue to support a few separations along folds and a couple of small holes at fold intersections. A binding trim at bottom left, with small loss of neatline, has been replaced with paper to accommodate framing.