Atlas géographique et physique du royaume de la Nouvelle-Espagne : fondé sur des observations astronomiques, des mesures trigonométriques et de nivellemens barométriques par Al. de Humboldt, 1812

The German Baron, Alexander von Humboldt, was a true savant; he was extraordinarily gifted as an explorer, geographer and naturalist. His genius becomes obvious when considering the maps he drew for his atlas while in Mexico City during his 1803 tour of New Spain. Working at the Real Seminaria de Meneria (the Royal School of Mines), Humboldt never ventured into the physical landscape he mapped. Instead he gathered every report, map and document he could obtain and began to reconcile them with all the astronomical observations he could locate

Humboldt’s “Map of the Kingdom of New Spain” was a remarkable cartographic achievement. According to Carl Wheat, as quoted in his Mapping the Transmississippi West, Humboldt’s map “was undoubtedly the most important and most accurate published map that had yet appeared.” Important enough that Humboldt’s great map of New Spain found its way into the hands of Zebulon Pike prior to his 1806 expedition to the Great Plains and Rocky Mountains. Humboldt would later complain bitterly to Thomas Jefferson when he saw his work reproduced, at least to a degree, in Pike’s maps of 1810.

Humboldt arrived in New Spain under royal patronage and was provided complete access to the collection of Spanish maps as well as the works of the best explorers and cartographers of the day, such as Alexander Mackenzie and Aaron Arrowsmith. His completed maps produced a synthesis of state-of-the-art cartographic knowledge, circa 1800. Yet for Humboldt this level of knowledge was not enough. Commenting in his Political Essay on the Kingdom of New Spain he noted with both exasperation and insight “it must be allowed that all that part of the west of North America is still but very imperfectly known” but perhaps “the journey of Captain (Meriwether) Lewis, at the expense of the Anglo-American government, on the Mississippi and the Missouri, may throw considerable light on this interesting problem.” It would indeed.

Of particular interest was Humboldt’s recognition that the “Stoney Mountains” of the north as noted by Mackenzie was a continuation of the Cordilleras of New Spain. What are now referred to as the Rocky Mountains begin to show themselves as the very backbone of the continent, with their imposing east-to-west width drawn with much more accuracy and detail than found on earlier maps. Humboldt also advanced the science of cartography by drawing his mountains with the hachure technique of shading as opposed to the less satisfactory method of showing mountains in profile. While admitting that the hachure system “forces the drawer to say more than he knows, more than it is even possible to know of the geological constitution of a vast extent of territory,” Humboldt felt the newer system outweighed this disadvantage. This technique was soon adopted universally, not to be replaced until the contour method of displaying mountains became popular many years in the future.

In place of imagining unconfirmed details for the still unmapped areas of the continent, Humboldt “chose rather to leave vacant space in my map than to draw from suspicious sources.” These spaces would begin to be filled with accuracy over the next two decades through American exploration. On the ground expeditions by Meriwether Lewis and William Clark, Zebulon M. Pike and Stephen H. Long would contribute to the growing base of geographic knowledge. This knowledge would redefine the way the West was viewed.