Map No. 4 — From the Valley of the Mud Lakes to the Pacific Ocean (Explorations and Surveys for a Railroad Route from the Mississippi River to the Pacific Ocean, Route near the 47th Parallel)

Cartographer: Capt. Edward G. Beckwith, 3rd Artillery, U.S. Army; F. W. Egloffstein, Topographer, 1855

Year: 1855

Prepared for Jefferson Davis’s Pacific Railroad Surveys, this sheet follows Beckwith’s 47th-parallel reconnaissance west from Nevada’s alkaline Mud Lakes across the Cascades to the Columbia River and Pacific coast. A crisp orange line marks the proposed rail axis, while delicate wash shading renders mountain massifs, volcanic plateaus, and dry basins in striking relief. Rivers, lakes, and selected forts anchor the sparse interior, and faint brown tints distinguish timbered uplands from desert flats. Longitudinal and latitudinal grids aid in plotting alternate passes and supply depots. The map’s east–west sweep reveals how engineers weighed steep Cascade grades against gentler basins to the south. As one of the few color plates in the survey atlas, it illustrates both the promise and the challenges of a northern transcontinental route long before the Great Northern Railway was built.