Louis Hennepin. “Carte de la Nouvelle France et de la Louisiane Nouvellement découverte.” In Description de la Louisiane, nouvellement découverte au Sud’Ouest de la Nouvelle France. Paris, 1683. The Tracy W. McGregor Library of American History

Belgian-born friar Louis Hennepin traveled to New France in 1675 as a missionary. Hennepin traveled with La Salle on his first expedition in 1678 and produced the first written description of Niagara Falls. Upon returning to France, he published Description de la Louisiane (Paris, 1683) along with an accompanying map, “Carte de la Nouvelle France et de la Louisiane Nouvellement découverte.” The place name “La Louisiane” appears for the first time on this map.

Louis Hennepin. “A Map of a Large Country Newly Discovered in the Northern America situated between New Mexico and the Frozen Sea.” In A New Discovery of a Vast Country in America. London, 1698. The Tracy W. McGregor Library of American History

Hennepin moved to Holland in the late 1690s, where he published Nouvelle découverte d’un très grand pays situé‚ dans l’Amérique entre le Nouveau Mexique et la mer Glaciale (Utrecht, 1697) and Nouveau voyage d’un pais plus grand que l’Europe (Utrecht, 1698). The former appeared in English in 1698 as A New Discovery of a Vast Country in Americaand contained “A Map of a Large Country Newly Discovered.” Although Hennepin’s accounts of his explorations were sometimes fanciful and inaccurate, his works were widely read and very influential in shaping views of North America.

Hennepin popularized the notion of an easy communication from the Missouri River system to waters flowing into the Pacific Ocean. “A Map of a Large Country Newly Discovered” locates the mouth of the Mississippi River (“Meschasipi”) too far to the west. The source of the Missouri River (“Otenta R.”) appears as a lake in the mountains and is close to the source of the Rio Grande ("River of Magdalen"). By locating the origin of these great rivers in close proximity in the mountains, Hennepin’s maps affirm the pyramidal height-of-land theory that dominated the geographic concepts of North America in the eighteenth century and had a major influence on the planning of the Lewis and Clark Expedition.

Thomas Jefferson owned first editions of all three of Hennepin’s works and consulted them in preparing his western treatise An Account of Louisiana, which he presented to Congress in November of 1803.

Louis-Armand de Lom d’Arce, baron de Lahontan. “A Map of ye Long River.” In New Voyages to North-America. London, 1703. The Tracy W. McGregor Library of American History

Louis-Armand de Lom d’Arce, baron de Lahontan, was the son of a prominent civil engineer in the court of Louis XIV. In the 1680s Lahontan went to Canada with the Bourbon Regiment. After serving for a time in western Canada, he returned to the East coast in 1688. Baron de Lahontan claimed to have traveled to the northern portions of the Mississippi River and to the villages of the Osage Indians on the Missouri River, but it was his journey to the Long River on his trip back that captivated the attention of adventurers who dreamed of finding a passage to the Pacific.

According to Lahontan, during a four-month journey in the winter of 1688-1689 his party of 300 men explored the Long River or, as it is labeled on his map, the “Rivière Morte” or “Rivière Longue.” The expedition traveled up the Long River about 800 miles from the Mississippi. At this point Indians told him that he was about 450 miles from a great salt lake located near some high mountains. Lahontan insisted that the Indians had shown him a deerskin map that depicted a large river running to the western sea and he suggests this passage to the Pacific Ocean on his own map. Lahontan’s widely published works were extremely popular in Europe. The Long River appeared on other maps as late as 1785.

Thomas Jefferson owned the second English edition of New Voyages to North-America (London, 1735). Despite the fact that Lahontan’s book was widely discredited by the second half of the eighteenth century, Jefferson deemed it an important work. He recommended it for inclusion in a national library in 1783 and later included it on a list of books relating to American travel that he called “a useful species of reading for an American youth.”

Guillaume Delisle. “Carte de la Louisiane et du Cours du Mississipi.” 1718. The Tracy W. McGregor Library of American History

The Delisle family replaced the Sansons as the preeminent family in the French school of cartography at the beginning of the eighteenth century. The most accomplished cartographer in the Delisle family was the child prodigy Guillaume, who became a member of the Académie royale des sciences at age twenty-seven and earned an appointment under Louis XIV as géographe du roi or royal geographer. Guillaume Delisle is considered the first modern scientific cartographer.

“Carte de la Louisiane et du Cours du Mississipi” shows an improved “Missouri R.,” which Delisle also labels “R. de Pekitanoni.” The map also represents a tributary of the Missouri very close to the course of the Rio Grande (“Rio del Norte”). An extension of the upper Missouri, labeled “Riv. Large,” runs to the west and around the northern edge of a chain of mountains. This river may have been based on Lahontan’s mythic Long River. “Carte de la Louisiane” is the first printed map to show the route of Hernando de Soto in 1539-1540; in addition, it traces the routes of other exploration between the Mississippi and the Rio Grande in the late 1600s and early 1700s. This is also the first map to refer to a variant of the name Texas (“Mission de los Teijas”).

Delisle’s “Carte de la Louisiane et du Cours du Mississipi” became the primary reference source for the lower Mississippi and lower Missouri river valleys and was used by other cartographers as late as 1797. This map is believed to be the oldest map consulted in the planning of the Lewis and Clark Expedition.

Herman Moll. “Map of North America to ye Newest and most Exact observations.” 1720. The Tracy W. McGregor Library of American History

Herman Moll began his career as an engraver and earned renown as the foremost map publisher in England in the early eighteenth century. Moll was one of the first mapmakers to use London as the prime meridian for longitude. British authorities used his “Map of North America” and his 1715 “A New and Exact Map of the Dominions of the King of Great Britain on ye Continent of North America” to counter French claims to territory in North America.

The “Map of North America” shown here is one of the last maps to depict California as an island. Moll claimed that he knew of seamen who had sailed around the island. Moll, who had engraved the maps in Baron de Lahontan’s Nouveaux Voyages de Mr. le baron de Lahontan, dans l’Amérique Septentrionale (The Hague, 1703), represents Lahontan’s “Morte or R. Longue” as a northern tributary of the Mississippi flowing due west to a large lake in the mountains. On the other side of the mountains he shows a river running westward toward, but not reaching, the Pacific Ocean.

Daniel Coxe. “A Map of Carolana and of the River Meschacebe.” In A Description of the English Province of Carolana, by the Spaniards call’d Florida, and by the French La Louisiane. London, 1722. The Tracy W. McGregor Library of American History

Daniel Coxe was the eldest son of Dr. Daniel Coxe of London, who received an immense land grant in the lower Mississippi valley from King Charles II. Daniel Coxe lived in the American colonies from 1702 to 1716. After returning to England he published an account of his travels and a description of the territory encompassed by his father’s claim.

“A Map of Carolana,” published in a promotional tract, is the first English map of the Mississippi valley. It improved on earlier maps by eliminating the mountains along the Mississippi River and by accurately positioning the Ozark and Appalachian mountains. Certain fanciful features of American geography, such as a shortened “Long River” and a very large “Lake of Thoyago” in New Mexico, however, still appear on Coxe’s map.

Although Coxe’s map is not considered a cartographic landmark, his book exerted considerable influence on geographical thinking about western North America by popularizing the concept of symmetrical geography. Coxe believed that the Mississippi valley demonstrated symmetrical geography and that the western slopes of what would be called the Rocky Mountains likewise mimicked the eastern slopes of the Appalachian Mountains. More important for the quest to find a passage to the western sea, Coxe promoted the notion of “an easy Communication betwixt the river Meschacebe [Mississippi River], and the South Sea.”

The “easy communication” foretold by Coxe helped convince a group of Albemarle County land speculators known as the Loyal Company to plan an expedition to the West in the 1750s. Joshua Fry of the Loyal Company and Thomas Jefferson each owned a copy of Coxe’s book.