2 volumes, 8vo (216 x 133 mm). Folding map with expedition route marked in red, 11 hand-colored chromolithographs, 9 woodcuts (some very light intermittent spotting, light offsetting.) Later full tan morocco gilt (rubbing, sunning to spines).

FIRST EDITION in English, the most extensively illustrated of all editions. Mollhausen wrote this work while traveling with the Whipple Expedition. This expedition, led by Lieutenant Amiel Weeks Whipple, was tasked by the War Department to survey potential transcontinental railroad routes across the United States, traveling from Fort Smith, Arkansas to Los Angeles along the 35th parallel north. The information gathered by the Whipple Expedition was later used in a 12-volume report now collectively known as the Pacific Railroad Surveys. Howes calls Mollhausen's book "the best account" of the Whipple Expedition's work. Cowan p. 435; Farquhar, Colorado River 19a; Graff 2849; Howes M-713; Rader 2418; Sabin 49915; Streeter S3134; Wagner-Camp IV:305; Wheat, Transmississippi 956.