It was November 1806. The explorers had gone without food for one day, then two. Their leader, not yet thirty, drove on, determined to ascend the great mountain. Waist deep in snow, he reluctantly turned back. But Zebulon Pike had not been defeated. His name remained on the unclimbed peak-and new adventures lay ahead of him and his republic.

In Citizen Explorer, historian Jared Orsi provides the first modern biography of this soldier and explorer, who rivaled contemporaries Meriwether Lewis and William Clark. Born in 1779, Pike joined the army and served in frontier posts in the Ohio River valley before embarking on a series of astonishing expeditions. He sought the headwaters of the Mississippi and later the sources of the Arkansas and Red Rivers, which led him to Pike's Peak and capture by Spanish forces. Along the way, he met Aaron Burr and General James Wilkinson; Auguste and Pierre Couteau, patriarchs of St. Louis's most powerful fur-trading family, who sought to make themselves indispensable to Jefferson's administration; as well as British fur-traders, Native Americans, and officers of the Spanish empire, all of whom resisted the expansion of the United States.

Through Pike's life, Orsi examines how American nationalism thinned as it stretched west, from the Jeffersonian idealism on the Atlantic to a practical, materialist sensibility on the frontier. Surveying and gathering data, Pike sought to incorporate these distant territories into the republic, to overlay the west with the American map grid; yet he became increasingly dependent for survival on people who had no attachment to the nation he served. He eventually died in that service, in a victorious battle in the War of 1812.

Written from an environmental perspective, rich in cultural and political context, Citizen Explorer is a state-of-the-art biography of a remarkable man.