Marvelous early strike of the second edition of this seminal map of the West. From 1846 to 1851, Mitchell and later Thomas Cowperthwait & Company used the same basic plate for the map of Oregon & Upper California, updating the information and later the title on a more than annual basis. In this second state of the map, 2 degrees of the Pacific have been removed and the map shifted east two degrees, to show more of the course of the Yellowstone River, and the regions just east of the Rocky Mountains. These early states of the second plate still contain errors, such as the ommission of the O in Mt. San Bernardino. In addition to adding counties in vivid color (many stretching nearly across the entirety of New Mexico and Utah, the map is much updated along the Rio Grande and south of Salt Lake. Many new trails are added, including Fremont's trails, Kearney, Col Cooke, etc. The Spanish or Los Angeles Route, Oregon Trail and Lewis & Clark Canoe Routes are still shown. This new edition, predating the Gadsden Purchase, shows the difference between Bartlett's line and Graham's Line, just east of Tucson, which is part of Mexico. Only Santa Barbara, San Luis Obispo, Mariposa, L.A. and San Diego Counties are shown. No counties East of the Cacades in either Oregon or Washington. Many other fascinating minor changes. A stunning dark impression with vivid color of this highly desireable map.