Relief shown by hachures. At head of title: Route near the 35th Parallel. Map no. 1. From U.S. War Department, Explorations and Surveys for a Railroad Route from the Mississippi River to the Pacific Ocean. Topographical Maps ... to Illustrate the Various Reports ... (Washington, 1859). Description derived from published bibliography. Inset: Sketch of Rio Pecos at Anton Chico. 20 x 15 cm.