A Chart of the Internal Part of Louisiana, 1810, 1895

U.S. Army Lieutenant Zebulon Montgomery Pike left St. Louis July 15, 1806 on his expedition to the Spanish borderlands while Lewis and Clark were still making their way home, somewhere on the upper Missouri River. The Governor of Louisiana Territory, General James Wilkinson, had directed Pike to explore the country of the Plains Indians and find the headwaters of the “Arkansaw” and Red Rivers. Besides instructions, Pike was also provided with Alexander von Humboldt’s map of the Great Plains and the Spanish territory of the Southwest, details of which made their way into Pike’s 1810 maps, to the consternation of von Humboldt. Regardless of the intrigue and ulterior motives on the part of Wilkinson that continues to swirl around his expedition, Pike’s travels resulted in several maps of historical importance describing the country directly west of St. Louis to the Rocky Mountains and south into Spanish New Mexico.

Pike saw his mission as one “to attach the Indians to our government and to acquire such geographical knowledge of the south-western boundary of Louisiana as to enable government to enter into a definitive arrangement for a line of demarcation between that territory and North Mexico.” Pike’s addition to the area’s geographic knowledge was soon transformed into a series of beautifully drawn maps by Anthony Nau. They offered a picture of the area based on actual exploration instead of rumors or the reports from trappers and voyageurs. Despite Pike’s many errors and misconceptions these documents remain significant achievements in the mapping of the American West.

But Pike’s maps did contain errors and misconceptions that bedeviled cartographers for decades. He insisted that the eastward flowing rivers of both the northern and southern Great Plains such as the Platte, Yellowstone, Arkansas and Red in addition to those flowing west towards the Pacific like the Columbia or south as does the Rio Grande all had a common continental source, reinforcing a long held geographic delusion. For Pike they were situated in a tightly confined area where “I can visit the source of any of those rivers in one day.” This misinformation would find its way into commercial maps until later expeditions like that of Major Stephen H. Long provided more accurate information.

Pike’s maps were valuable in redefining the Great Plains’ dimensions, particularly its east-west distances, with more accuracy then previous maps of the region and were the first such documents to bear the stamp of “official surveys.” They also suggested the hopefulness Americans invested in their interpretations of the West. If a common source for western rivers existed, this optimistically suggested an easy route to the Pacific. Pike’s expectations were not unusual for an American whose preconceptions of the West were drawn from his knowledge and experience with the nation’s eastern geography. As geographer John Logan Allen notes, early mapping was often “mapping of the geography of hope and expectation rather than the geography of reality.” This kind of cultural “slipperiness” so often found its way into maps.