Oregon Historical Quarterly

 OHQ vol. , no.  James v. Walker Henry S. Tanner and Cartographic Expression of American Expansionism in the s©  Oregon Historical Society americans’ concept of their nation’s sovereignty extending to the Pacific Ocean developed gradually and hesitatingly during the first three decades of the nineteenth century.Rhetoric about American interests in the Pacific Northwest included intermittent but intense international diplomatic conversations, presidential messages, congressional debates, editorial commentary in newspapers and other periodicals, and increasingly interested and opinionated cartographical literature. All these layers of discourse were linked by their focus on a geographical area and by geopolitical events centered on that area. That discourse contributed to a gradually developing image of an American dominion of continental proportions. Diplomats, congressmen, newspaper editors, and mapmakers were all involved in the development of that image but were not bound by similar conventions in the construction and communication of their visions. American commercial mapmakers of the period contributed to the development of a national consciousness of American expansion into the Pacific Northwest — a place still controlled by Native peoples — by both describing and interpreting national and international events. During the second and third decades of the nineteenth century, the unique contributions of cartographers John Melish and Henry Schenck Tanner helped establish a national identity in ways that were visionary,  Walker, Henry Tanner, Maps, and American Expansionism in the s influential, and powerful. Their maps contained information that was both geographical and geopolitical. In the Pacific Northwest, the main “new” features on updated editions of maps were often boundaries, legends, toponyms , and color codes that reflected the actions of non-Native diplomats and congressmen rather than explorers, topographers, and settlers. The maps graphically represented how American cartographers legitimized the expanding domain of one cultural group and,at the same time,delegitimized the sovereignty of both other imperial nations and Native Americans in the Pacific Northwest. At the beginning of the nineteenth century, the United States, Great Britain, Spain, and Russia all claimed sovereignty to some portion of the This detail of A Map of Lewis and Clark’s Track Across the Western Portion of North America, published in , was the most informative map of the Pacific Northwest at the time. Geopolitical events of the following decade resulted in John Melish and Henry Tanner drawing maps that promoted expansion of American sovereignty in the region, despite the presence of large populations of Native Americans. Both cartography and geopolitical rhetoric helped construct an image of a distinct place in the Pacific Northwest called “Oregon.” OHS digital no. bb  OHQ vol. , no.  Native-controlled lands of the Pacific Northwest. By the middle of the second decade, Americans claimed rights principally on the basis of three historical events:Robert Gray’s discovery and naming of the Columbia River in May ; the military sponsored Expedition of Meriwether Lewis and William Clark from  to ; and the establishment of the private (but government sanctioned) fur trading enterprise at Astoria in . In the aftermath of the War of , Anglo-American tensions increased regarding several issues, including contested areas of sovereignty in the Pacific Northwest. Still, American diplomatic activity regarding this region was restrained,and there was almost no physical presence of American military or commercial enterprise. Following the Treaty of Ghent in December , formal restitution of Astoria from the British to the United States was delayed until August . The American government sanctioned maritime explorations to the Northwest coast in  and  but aborted them to more pressing needs for naval forces elsewhere. Neither American nor British diplomats attempted treaty-making with any tribes of the region during this time. In contrast, publisher John Melish, an established and influential mapmaker in Philadelphia,advocated a more overt and opinionated position of American sovereignty in the Pacific Northwest.In ,he published his Map of the United States with the contiguous British and Spanish possessions . . . (Figure ). Scholars have widely regarded this map as the first to portray the United States extending from the Atlantic to the Pacific ocean. Indeed, in his accompanying Geographical Description, Melish stated:“The map . . . shows at a glance the whole extent of the United States territory from sea to sea.” On the map,Melish extended the parallel of  degrees and  minutes across the Rocky Mountains...