THE MAPPING OF THE GREAT LAKES1670—2007
by Christopher Baruth
The mapping of the Great Lakes region began in the early seventeenth century, when the first indications of the lakes appeared on maps made by European cartographers. By the mid-1600s, the maps of French Royal Geographer Nicolas Sanson had recognizable depictions of all five Great Lakes. His map is imprecise—Lake Superior lacks its distinctive shape and is unbounded on the west—but Lakes Ontario, Erie, Huron and Michigan can be discerned without difficulty. The lack of any reference to the Mississippi River in Sanson’s map reflects how little cartographers really knew about the region at the time.
Until the late eighteenth century, maps were made with information acquired in an irregular and imprecise manner. They were not based on formal surveys, but on written records supplemented with sketches by explorers, missionaries and trappers traveling the Upper Midwest. European cartographers had the task of fitting together this often contradictory information and putting the results into the framework of a geographic map. Instead of being mapped in terms of latitude and longitude, prominent places were usually located in relation to other places, which were, of course, similarly positioned. Distances could not be measured with any accuracy at this time, so these maps were liable to gross errors.
The early maps in the “Making Maps, Mapping History” exhibit provide a capsulized view of the growth of geographical knowledge of the Great Lakes region. As noted above, Sanson’s map was the first to display all five of the Great Lakes. Vincenzo Maria Coronelli, the cosmographer of the Republic of Venice, used information supplied by Jesuit missionaries in a 1688 map that was the first accurate depiction of the Great Lakes and the Mississippi River. French cartographer Guillaume De L’Isle further refined the image and provided an outline that was not substantially improved until surveyors entered the region in the nineteenth century.
The first official government surveys of the Great Lakes were hydrographic surveys conducted by the British Admiralty under the direction of Capt. Henry W. Bayfield. Bayfield spent his entire career surveying the St. Lawrence River and the Great Lakes, beginning with Lake Superior in 1816. The lake-shore city of Bayfield, Wis., was named in honor of this pioneer surveyor.
One of the first acts of the new government of the United States was to establish a system for the orderly settlement of its western lands. Under the Ordinance of 1785, land surveyors went into the western territories in advance of settlement to divide the land into townships of 36 square- mile sections. Though mapping was not the government’s primary aim, the surveys provided ample grist for the mapmaker’s mill, and the regions were, for the first time, mapped with considerable accuracy. The federal government, however, was not yet in the business of making maps for the public. That was left to enterprising individuals, such as Samuel Morrison, Elisha Dwelle and Joshua Hathaway, who produced one of the first topographical maps of the Wisconsin Territory in 1837.
The surveys of the General Land Office served as the basis for the mapping of much of the Great Lakes region from around 1800, when the surveys began, until about 1890, when the U.S. Geological Survey began to map the region again. In some cases, however, the old surveys were not entirely superseded until the mid-20th century. The distinctive feature of maps based on these surveys is the invariable presence of the township grid.
As population and commerce in the Great Lakes region grew, the federal government assumed responsibility for charting the lakes for navigation. The U.S. Lake Survey began in 1841 with an appropriation of $15,000. Before the Civil War, the work was conducted by officers of the Corps of Topographical Engineers. Its initial survey was completed in 1882, but the need for contin- uous revisions caused it to be reactivated a few years later. The Topographical Engineers merged with the U.S. Army Corps of Engineers in 1863, and the Lake Survey remained in the hands of the Corps of Engineers until 1970, when it became part of the newly formed National Ocean Survey (now known as the National Ocean Service).
The U.S. Lake Survey conducted far more rigorous surveys than those of the General Land Office, which used instruments no more sophisticated than a surveyor’s compass and a Gunter’s chain. The Lake Survey used an array of precision instruments and employed triangulation to form the geographic framework of the maps. Triangulation allowed the transfer of geographical coordinates from point to point throughout the system and, for the first time, geographical locations were determined with precision. Inland navigation prompted Congress to order a variety of government surveys. During the era of canal building, surveys like the one for the Portage Canal were common. Most of them were conducted by the Corps of Engineers, as were the surveys of the great rivers, such as the Mississippi.
The degree of accuracy accorded Great Lakes navigators was generally not matched on land for many years to come. The task of precisely mapping the United States by covering it with large-scale topographic quadrangle maps was given to the newly formed U.S. Geological Survey (USGS) in the 1880s. John Wesley Powell, the second director of the USGS, stated that the mapping of the United States could be accomplished in 25 years, but that goal was not accomplished until the 1980s. The first topographic maps of Wisconsin appeared in the 1890s, when much of the southeastern part of the state was surveyed. The surveys were quickly done, however, and most of the sheets needed at least minor revision within the next decade. Despite a rapid start, the topographic mapping of Wisconsin bogged down and ultimately was not completed until 1983. Mapping standards changed entirely with the application of aerial photography around 1930. Following World War II, all Wisconsin topographic sheets were derived from photographs.
Today, polar-orbiting satellites with thematic mappers can, in a single day, record images that reveal Great Lakes water quality and temperature, the streets and large buildings of urban areas, and the general health of forests, wetlands and farmlands, including the identity of such crops as corn, hay and alfalfa. The detailed precision of today’s computerized Space Age technology no doubt would have astounded Nicolas Sanson—but the seventeenth-century mapmaker’s ability to create a fairly accurate map of a world he had only heard and read about is equally astounding to twenty-first-century mapmakers.