4to (285 x 218 mm). Engraved folding map after Clark by S. Lewis, 5 engraved maps and plans on 3 leaves; half-title. Modern quarter calf antique, uncut. FIRST ENGLISH EDITION OF THE AUTHORIZED ACCOUNT OF "THE MOST IMPORTANT WESTERN EXPLORATION" (Howes). Lewis and Clark intended to publish their journals after the completion of their 1804-1806 expedition, but their official duties and Lewis's death in 1809 delayed publication. Nicholas Biddle edited the text of the first American edition with the assistance of Paul Allen, and the first edition was published in Philadelphia in 1814. The present edition was edited by Thomas Rees from sheets of the first American edition; he notes, "the only liberty that has been taken with the language, has been merely the correction of a few inadvertent grammatical or typographical errors" (p. xiv). His introduction includes Jefferson's "Message on the Subject of this Expedition" of 19 February 1806 (pp. viii-ix) and an extract from Lewis's "Fort Mandan" letter of "17" [i.e. 7] April 1805 to Jefferson (pp. x-xii). Hill, p.180 ("one of the most interesting narratives of North America in existence"); Sabin 40829; Wagner-Camp 13.