Nicholas King. “Map of the Western part of North America.” 1803. Courtesy of the Geography and Map Division, Library of Congress

English-born Nicholas King came to the United States in 1794 and worked as a surveyor in Philadelphia. In 1796 and 1797 he served as the first surveyor of Washington, D.C. Over the course of his career, King prepared maps related to the expeditions of Lewis and Clark, William Dunbar, Zebulon Pike, and others.

In March 1803, U.S. Secretary of the Treasury Albert Gallatin asked King to prepare a comprehensive new map of western North America for the Lewis and Clark Expedition. Gallatin, who shared Jefferson’s lifelong interest in science, geography, and the Indian cultures of North and Central America, played an active role in planning the expedition. He instructed King to incorporate the work of Ellicott, Cook, Vancouver, Arrowsmith, Mackenzie, Thompson, Mitchell, d’Anville, and Delisle into his map.

Although it copies liberally from the western portion of Aaron Arrowsmith’s 1802 map of North America, the King map synthesizes the most advanced representations of the Missouri River system, including its relationship to the Pacific Northwest. Unlike Arrowsmith, King shows the northern branch of the Missouri as the main branch of the river and represents the northernmost source of the Missouri closer to the Great Lake River on the western slopes. The King map also differs from Arrowsmith’s in that it depicts the Rocky Mountains not as a long, solid chain of mountains but as a shorter range that ends in today’s Montana. Gaps in the range near the present-day Canadian border suggest the possibility of an easy crossing of the Continental Divide. In addition, King’s map affirms the pyramidal height-of-land theory by situating the source of the Rio Grande on a high plateau near the source of the Columbia River.

Visit Library of Congress's web page about King’s “Map of the Western part of North America.”

Portrait of William Clark by Charles Willson Peale, ca. 1810. Courtesy of Independence National Historical Park, National Park Service

William Clark, whose family resided for a time near Charlottesville, was the younger brother of Revolutionary War hero George Rogers Clark. William Clark joined the army at nineteen and later served a command on the Mississippi River. During this time, he became Meriwether Lewis’s commanding officer and the two men struck up a friendship.

After Jefferson selected Lewis to lead the expedition to the Pacific, Clark eagerly accepted Lewis’s offer to share the command. Following the expedition, Clark served as superintendent of Indian Affairs and then governor of the Missouri Territory.

William Clark. “A Map of part of the Continent of North America.” 1810. William Robertson Coe Collection of Western Americana, Beinecke Rare Book and Manuscript Library, Yale University

In preparation for the expedition, Clark trained himself to be an able cartographer. During the winter of 1803-1804 he studied the maps and geographic information that Lewis brought to Camp Dubois near St. Louis and practiced using the sextant and the octant. Before the Corps of Discovery left the St. Louis area, Clark produced a map of part of upper Louisiana and a table of distances to the Pacific coast. By the spring of 1805, when the expedition team had advanced as far as Fort Mandan, Clark had produced the route maps of the Missouri River from St. Louis and a general map of the Missouri River system and the Northwest.

Twenty-eight arduous months after setting off, the Lewis and Clark Expedition returned to a triumphant welcome in St. Louis on September 23, 1806. Clark brought with him an updated map of the West that he had prepared the previous winter. Over the next few years Clark continued to update his map, producing in 1810 the version shown here. This map includes information gathered from several new expeditions to the West, including the 1807-1808 explorations of the Yellowstone basin by Corps of Discovery members George Drouillard and John Colter.

Clark’s map surpasses its predecessors by presenting a radically new and remarkably accurate view of the upper Missouri and its connections with the Columbia River basin. The map depicts the western mountains as multiple ranges rather than a single strand of mountains. This advance in geographical knowledge finally extinguished the idea of a Northwest Passage to India via the Missouri River and marked the end of the long-cherished hope of finding a short portage to the Pacific.

Clark’s original map is in the William Robertson Coe Collection of Western Americana, Beinecke Rare Book and Manuscript Library, Yale University.

Portrait of Meriwether Lewis by Charles Willson Peale, ca 1807. Courtesy of Independence National Historical Park, National Park Service

Meriwether Lewis was born in Albemarle County, Virginia. His name reflects the union of two families—the Meriwethers and the Lewises—who were early settlers and large landholders in the Albermarle area. In 1801 Jefferson selected Lewis to be his personal secretary. Two years later, Jefferson chose him to lead the expedition to the Pacific Ocean. After returning from the expedition, Lewis was appointed governor of the upper Louisiana Territory, a post he held until his death in 1809.

“A Map of Lewis and Clark’s Track.” In History of the Expedition under the Command of Captains Lewis and Clark,...1814. The Tracy W. McGregor Library of American History

Jefferson’s instructions for the Lewis and Clark Expedition reveal that he expected the expeditionary team to gather a wealth of scientific and geographic data. On the expedition, Lewis wrote Jefferson that “We have encouraged our men to keep journals, and seven of them do so.” Lewis took responsibility for recording the scientific findings of the expedition, including observations on flora, fauna, minerals, Indian languages, and celestial and geographic conditions. William Clark, meanwhile, concentrated on charting the expeditionary route, preparing maps, and logging each day’s events.

Jefferson expected Lewis to turn the raw notes and data he had amassed on the expedition into a finished “scientific” account. Lewis had made only limited progress on this project at the time of his death in 1809. The completion of the work fell to William Clark. Clark arranged for Nicholas Biddle, a respected scholar and writer in Philadelphia, to prepare the official journals of the expedition for publication. Biddle eventually hired Paul Allen to complete the editing. In 1814 Allen issued a two-volume set of the journals, History of the Expedition under the Command of Captains Lewis and Clark. The published journals included “A Map of Lewis and Clark’s Track, Across the Western Portion of North America From the Mississippi to the Pacific Ocean,” a version of Clark’s 1810 map.

Meriwether Lewis. History of the Expedition under the Command of Captains Lewis and Clark, to the Sources of the Missouri, Thence across the Rocky Mountains and down the River Columbia to the Pacific Ocean. Performed during the years 1804-5-6 . . . . Paul Allen, editor. Philadelphia, 1814. The Paul Mellon Collection

The copy of History of the Expedition under the Command of Captains Lewis and Clark shown here is in original boards—one of the few such copies extant. Many book collectors had their volumes rebound and did not preserve the original front and back covers. These covers contain advertisements for other books being sold at the time of publication.