Map No. 1 from San Francisco Bay to the Northern Boundary of California

Cartographer: Lieutenant R. S. Williamson, U.S. Topographical Engineers, and Lieutenant H. L. Abbot, U.S. Topographical Engineers, with assistants H. C. Fillebrown, J. Young, and C. D. Anderson (1855)

Year: 1855

Prepared for the Pacific Railroad Surveys, this hand-colored sheet follows Williamson and Abbot’s reconnaissance north along the Coast Range and through the Klamath Mountains to the Oregon line. A bold yellow wash traces the main exploratory route, while a lighter tint marks alternate passes and valley approaches. Shaded relief vividly depicts the rugged Trinity, Shasta, and Siskiyou uplifts that challenged any rail alignment, and isolated green patches highlight fertile river bottoms such as the Sacramento and Shasta Valleys. Lakes, emerging towns, and Hudson’s Bay Company trails appear sparingly, underscoring the region’s sparse Euro-American settlement in the mid-1850s. Latitude–longitude grids and a mileage scale let engineers gauge grades and distances between candidate passes. The map offers an invaluable snapshot of Northern California topography before large-scale railroad construction and intensive mining reshaped the landscape.