Jonathan Carver (1710-1780) of Massachusetts joined in Robert Rogers’s efforts to find a route to the Pacific Ocean. In 1766 Rogers sent Carver to map the upper Mississippi basin in preparation for a western expedition. Carver crossed Lake Michigan, traversed the Fox and Wisconsin rivers to the Mississippi and then traveled up the St. Peter River, or Minnesota River. He was the first English-speaking explorer to venture west of the upper Mississippi River. After wintering with the Sioux Indians, Carver backtracked the next spring to Prairie du Chien in present-day Wisconsin where he met the expedition sent by Rogers. When supplies failed to arrive, however, the expedition was abandoned.
In 1769 Carver went to England where, in 1778, he published the accounts of his travels. Carver’s book is notable for endorsing the height-of-land theory and anticipating the idea of a continental divide. According to Carver,
The four most capital rivers on the Continent of North America, viz. the St. Lawrence, the Mississippi, the River Bourbon [today, the Nelson River], and the Oregon or the River of the West, . . . have their sources in the same neighborhood. The waters of the three former are within thirty miles of each other; the latter, however is rather further west.
Carver’s map shows the “Mantons R.,” or the upper Missouri, starting near the sources of a truncated Missouri River and the Mississippi River. The “Mantons R.” flows westward to “Pikes Lake,” which is connected by a dotted line to the “River of the West.” While this route represents a convenient passage to the Northwest, Carver’s book is the first to mention a large mountain range to the south (presumably the Rocky Mountains) that blocks the westward passage and serves as a continental divide.
The above map is included in the third English edition (1781) of Travels Through the Interior Parts of North America. Carver’s bestselling book appeared in over thirty editions. Thomas Jefferson owned a 1797 edition. The book brought the word Oregon into popular use and supported the notion of the noble savage then gaining acceptance in European literary circles. Carver borrowed extensively from earlier books by Hennepin, Lahontan, and Charlevoix. Some critics believe Carver did not actually observe what he claimed he saw and that his travel journal may be the work of another. A 1792 letter to the American geographer Jedediah Morse claimed that Carver “doubtless resided a number of years in the western country, but was an ignorant man, utterly incapable of writing such a book.”