Finely detailed map of Oregon and Washington, prepared in connection with the US Pacific Railroad Surveys.
From the surveys of R.S. Williamson in California, this map provides the general overview for all of the USPRR surveys in California to date.
The map provides a fine overview of the exploration and surveying of this region up to 1855, in connection with the US Government's attempt to locate the most practicable routes for the transcontinental railway.
Wheat calls this a "monumental document," remarking that with few exceptions, "the routes of the railroads projected on this map became the actual routes selected, which endure to modern times."
The map covers the region from Bodega Bay in the north to below San Diego. The proposed Railroad Route is shown from Ft. Yuma, Arizona to San Francisco and Martinez just across the bay from Benicia.
For these surveys, two parties were utilized, one led by Lieutenant R.S. Williamson and another by Lieutenant J.G. Parke.