A good case can be made that Simeon De Witt's landmark A Map of the State of New York (1802) is the most important map ever made of the Empire State. [ 1 ] As shown in Figure 1, it was certainly the most significant and influential map of the state published between 1784 and 1830.
Figure 1. Simeon De Witt, Map of the State of New York (1802).
Library of Congress.
There are several reasons why De Witt's map is so notable. It is the first detailed, large-scale map of the state produced after the American Revolution. It is one of the first maps to show the state with what are nearly its modern boundaries. It is considerably more accurate than its predecessors. And it sheds a good deal of light on the rapid development of northern and western New York in the years following the conclusion of the Revolutionary War.
How did this map come into being? That question is the subject of this article. The answer reveals the remarkable continuity between De Witt's map and its colonial predecessors, and tells us much about the development of cartography in the early years of the American Republic.
The general outlines of the career of Simeon De Witt (1756-1834) are well known, and the details can be found elsewhere.[ 2 ] To summarize, he was related to General James Clinton (1733-1812), and to governors George Clinton (1739-1812) and De Witt Clinton (1769-1828). He attended Queens College (now Rutgers University), and received his initial training as a surveyor from his uncle James Clinton. At this uncle's recommendation, in 1778, Washington appointed him an assistant to Robert Erskine, the Geographer and Surveyor General of the Continental Army, a position that he occupied after Erskine's death in 1780. De Witt's experience as a military surveyor made him one of the few highly qualified cartographers in America. He belonged to an elite circle of surveyors and geographers, which included such luminaries as David Rittenhouse, Thomas Hutchins, and Andrew Ellicott. He was also politically well connected—his relationship to the Clinton family placed him at the center of New York politics.
The bulk of De Witt's career was spent as New York's Surveyor General between 1784 and 1834. In this influential position, he had many duties besides surveying and mapping. Especially in the early years of his career, his primary task was running a very active land office, which was in charge of disposing of lands confiscated from former loyalists, or acquired from the Iroquois in central and western New York.[ 3 ] In his later years, he was involved in a number of important projects, including the surveying and construction of the Erie Canal. He was also one of the commissioners who drew up the street plan that guided the development of Manhattan.
De Witt commenced work on his map of New York State shortly after assuming office as Surveyor General in 1784. Having a detailed and accurate map of the state was important for many government functions, not the least of which was the sale of land.
De Witt was by no means the first person to make a map of New York. He had many colonial predecessors, and in the late colonial period, Samuel Holland, John Montresor, and Claude Joseph Sauthier made relatively detailed maps of the province of New York. These maps I have described in another article on the New York Map Society web site.[ 4 ]. The latest and most detailed of these colonial maps is Claude Joseph Sauthier's Chorographical Map of the Province of New York, which was widely regarded as the best large-scale map of New York prior to the appearance of De Witt's map in 1802. A glance at the major features of Sauthier's map—which is illustrated and described in the article linked to this one in Note 4—provides perspective for understanding De Witt's achievement.
New York, as portrayed by Sauthier, was very different from the New York we know today. Most notably, the boundaries do not much resemble those of contemporary New York. Only the boundaries with New Jersey, Connecticut, and Canada were approximately the same as they are today. The boundary with Massachusetts was undetermined, and most of the boundary with Pennsylvania was unsurveyed. Vermont at that time officially belonged to New York. Most of northern New York was virtually uninhabited. Above all, central and western New York were not included on Sauthier's map, since this area still belonged to the Iroquois, and very little was known about its geography.
It should be noted that Sauthier and his predecessors made their maps by a process of collation. Since they lacked the resources to survey the province systematically, they put together their maps from a variety of sources. They copied from previous maps, and updated and modified the work of their predecessors with information obtained from a wide range of sources of varying reliability—including boundary surveys, surveys of limited areas (such as large estates), and military route surveys. As we will see, De Witt followed much the same procedure, although by 1802 had much more to work with.
When De Witt assumed office in 1784, he had at hand a relatively small amount of geographical information about the state. Of course, he had printed maps, such as those of Sauthier and Montresor. He also had access to the route surveys and other military maps that he and Erskine had made for the Continental Army.[ 5 ] These military surveys provided good coverage of the roads and other features of the lower Hudson Valley north of the Highlands—an area of great strategic importance for the American Army. De Witt would also have been familiar with the remarkable route maps of the Finger Lakes area produced by the Clinton-Sullivan expedition against the Iroquois.[ 6 ] He apparently had very little of the detailed property mapping that was done in the final decades of the colonial era. Soon after taking office as Surveyor General, De Witt wrote to Jeremiah Rensselaer asking him for permission to copy any maps he had of colonial land patents, as “the papers belonging to the Surveyor General's office before the war are not to be had.”[ 7 ].
One of De Witt's first undertakings was to attempt to reconstruct the old colonial land holdings using Sauthier's map and other sources. This was of vital importance for the state, which needed to resolve disputes over conflicting claims to colonial land patents, many of which had been held by Loyalists, and had been forfeited during the Revolution. A dramatic illustration of the situation created by these contested claims is the series of court cases involving William Cooper and the lands around what later became Cooperstown.[ 8 ] De Witt's most impressive contribution to this sorting out process is his Map of the Head Waters of the Rivers Susquehanna & Delaware Embracing the Early Patents on the South Side of the Mohawk River (ca. 1790), seen in Figure 2 [ 9 ].
Figure 2. Detail of DeWitt's map of land patents south of the Mohawk River. New York State Library
Of particular importance for De Witt's efforts to produce a map of New York was the settlement of the state's boundaries. The disputes with Massachusetts over the boundary between the two states, and Massachusetts' claim to most of what is now western New York, were settled in 1784. In 1789, Governor George Clinton grudgingly gave up New York's claim to Vermont. These agreements meant that the boundaries between New York, Massachusetts, and Vermont could be surveyed. Since these lines had to be measured carefully, the resulting surveys provided De Witt with boundary lines that could be used to ascertain the location of land parcels along their length, as well as to determine more accurate latitudinal positions along New York's eastern boundary.[ 10 ]
By far the most important of these boundary surveys for the future mapping of New York was the survey of the line between New York and Pennsylvania along the forty-second parallel.[ 11 ] This survey, which commenced at the point where the latitudinal line crossed the Delaware River, was carried out in 1785 and 1786. The boundary survey was conducted by a stellar team that included David Rittenhouse and Andrew Ellicott for Pennsylvania, and Philip Schuyler, James Clinton, and De Witt himself for New York. It must be said that the Pennsylvania part of this team outclassed the New Yorkers, including De Witt. Although De Witt was a capable surveyor, he was not at the cutting edge of his profession in comparison to Rittenhouse or Ellicott.
This survey was conducted using an innovative method devised by Ellicott, which improved on the procedure used by Mason and Dixon to survey the southern boundary of Pennsylvania. It relied on instruments devised by Rittenhouse, which were better than anything available in New York.[ 12 ] The survey involved the measurement by astronomical means of a large number of latitudes, which were used to correct the survey line for the curvature of the earth. This survey occupies an important place in the mapping of America. A recent commentator has written: “… the way in which the Pennsylvania-New York boundary was run would become the prototype for nearly all subsequent east-west borders in the United States, including the immense frontier with Canada.”[ 13 ]
The long latitudinal line separating New York and Pennsylvania was particularly important for the future mapping of New York. The survey, which later surveyors confirmed to be accurate to within one foot per mile, was marked by milestones. The milestones were later used as starting points for north-south meridians that were drawn across much of the state—thus helping to establish a partial grid of longitudes and latitudes for locations in central and western New York.
The importance of this survey for the mapping of New York is revealed by an important regional map by John Adlum and John Wallis (Figure 3). This map was published in 1791 under the title Map Exhibiting a General View of the Roads and Inland Navigation of Pennsylvania and Part of the Adjacent States.[ 14 ] Pennsylvania-based surveyor John Adlum (1759-1836) was involved in surveying the boundary between New York and Pennsylvania, and had land interests in southern New York. His map provides a good overview of existing geographic knowledge of all of New York south of the Mohawk River, except for eastern Long Island. It also shows very clearly the Erie Triangle and New York's western boundary, and it displays the location of the Six Nations with a prominence that does not appear on later maps.
Figure 3. Detail of John Adlum, Map…of Pennsylvania and Adjacent States (1791).
1861 reprint with different title from New York State Library.
An unusual and telling feature of the Adlum map is its use of a prime meridian based on the intersection of the 42nd parallel with the Delaware River—the starting point of the New York-Pennsylvania east-west boundary line (see illustration above). This is probably the only map ever made based on this particular prime meridian, rather than on a more conventional location, such as Greenwich, Paris, or even New York City.
Adlum's use of this peculiar prime meridian illustrates the difficulty American surveyors still had in ascertaining correct longitudes. Although the use of the chronometer to measure longitudes was becoming increasingly widespread in Europe in the last quarter of the eighteenth century, its use did not become established in the United States until the first decades of the nineteenth century. Ellicott and Rittenhouse both laboriously made a few astronomical measurements of longitudes—one of which was Ellicott's determination of the southwest corner of the Pennsylvania boundary. However, there is no evidence that Ellicott directly determined any longitudes along the Pennsylvania-New York boundary, which explains Adlum's use of this unusual prime meridian. It would have been possible to estimate the longitude of the starting point of the line on the Delaware River from Greenwich by measuring from New York or Philadelphia, or even by measuring along the Pennsylvania boundary from its southwest corner, but evidently the survey team considered such methods to be insufficiently reliable. It should be noted that, as late as 1806, De Witt estimated the longitude of Albany by measuring its distance from Philadelphia.[ 15 ]
The point of this somewhat technical excursion is that, in constructing his map of New York, De Witt had to work without precisely defined longitudes for specific locations. The latitudes of a number of places were fairly well known, but De Witt was not in a position to construct his map around a framework of astronomically determined locations. Instead, he had to rely largely on measured distances from one place to another.
This is why the boundary with Pennsylvania played such an important role in the mapping of New York. Its milestones provided a string of known longitudinal locations relative to its unusual “prime meridian” for all of central and western New York. This whole area was in the process of being divided up into huge parcels, which were surveyed between 1785 and 1800. The most prominent of these were the New Military Tract in the Finger Lakes area, the Holland Purchase (which included most of the state west of the Genesee River), and the Phelps-Gorham Purchase, which lay between the other two. [ 16 ]
These tracts of land were surveyed semi-systematically and in somewhat different ways. In the case of the Phelps-Gorham Purchase, a faulty survey had to be redone. The surveyors of these gigantic tracts divided them up into rectangular “townships,” which were not units of government (like New England townships), but rather arbitrary units to facilitate the surveying and sale of land. These township grids were bounded by north-south lines, which were, directly or indirectly, based on known locations on the Pennsylvania boundary.
The rectangles forming these grids could be subdivided indefinitely down to the level of lots for sale to individual settlers. This system of laying out the land was very similar to the rectangular survey system, which was being implemented by the federal government in these years. One result of the use of this system was that large areas of central and western New York were more-or-less systematically surveyed—thereby providing a fairly reliable framework for large parts of De Witt's future state map.
De Witt himself was in charge of surveying the lands of the “New Military Tract” in Central New York. This was a large block of land in the vicinity of the Finger Lakes, which was set aside for the use of New York soldiers who had served in the Revolutionary War. This land, which amounted to more than 1.5 million acres, had been acquired through treaties with Onondagas (1788) and Cayugas (1789). It was surveyed under De Witt's supervision between 1789 and 1793 by teams headed by Moses DeWitt and Abraham Hardenbergh.
The surveyors working for De Witt were mostly trained on the job, and had limited scientific and mathematical skills. Their surveys were conducted by chain and compass. De Witt made no effort to have them correct their maps for the curvature of the earth or for magnetic variation. Instead, he issued very basic instructions on how lots should be surveyed and numbered. These are on the order of: “Whenever it can be conveniently done make the sides of townships North South East and West magnetically.”[ 17 ] De Witt wrote little about how the surveys under his direction should be conducted, but some of his later communications help fill out the picture. In 1808, he issued printed instructions to his assistants on how to observe variations in the magnetic needle.[ 18 ] These instructions, which resemble those of his colonial predecessors, in theory made it possible to determine the actual north-south orientation of individual surveys. His letters also contain occasional admonitions to surveyors on such matters as making certain that the length of their chains had not changed because of their stretching through use.[ 19 ]
The New Military Tract is famous for the (mostly) classical place names assigned to its townships. De Witt had originally numbered the townships, and the place names were probably chosen by the New York State Land Commission. The commissioners ignored almost all of the old Iroquois place names in this area, and substituted classical and literary names. The New Military Tract included the townships Lysander, Manlius, Pompey, Homer, Solon, Cincinnatus, Scipio, and Brutus, along with modern heroes of literature, such as Milton, Locke, and Dryden. This renaming of conquered lands is a characteristic feature of European and American expansionism.[ 20 ]
Some of the surveys conducted in western New York were technically more advanced than those of De Witt. The best of them were carried out by Andrew Ellicott or his brother Joseph, who was responsible for surveying the Holland Purchase. In 1791, Andrew Ellicott and others carried out a resurvey of the “preemption line,” which divided the New Military Tract from the lands to the west. West of this line, the right to purchase land from the Indians had been deeded to Massachusetts, which promptly sold the rights to private speculators. These lands were part of the Phelps-Gorham purchase, and had been imperfectly surveyed in 1788-89. Andrew Ellicott's resurvey involved drawing a meridian from the Pennsylvania boundary to Lake Ontario using astronomical observations and the newly invented surveyor's transit, rather than the usual compass and chain technique. This laborious process required making numerous astronomical observations, and cutting down trees to obtain a straight line of sight for the transit. This resurvey resulted in a more precise measurement of the north-south meridian along the preemption line. It was accepted by De Witt, who accordingly modified the western boundary of the New Military Tract. De Witt can be credited with the good judgment to recognize and accept superior work.[ 21 ]
Joseph Ellicott used essentially the same technique in 1797, when he surveyed the eastern boundary of the Holland Purchase. After Simeon De Witt, Joseph Ellicott was arguably the most important figure in the mapping of New York during this period.[ 22 ] De Witt made him a deputy Surveyor General, and thereby gave official status to his surveys of western New York. De Witt even authorized him to survey the boundary between the Holland Land Company's lands and a strip of state land along the Niagara River.[ 23 ] Ellicott was a capable surveyor, who had received his training from his brother, Andrew Ellicott. Joseph Ellicott has left us detailed descriptions of his surveying techniques, which are spelled out in his reports to the Holland Land Company.[ 24 ]
Generally, Ellicott's methods of surveying were similar to De Witt's, but Ellicott was a little more precise and systematic, and his methods were somewhat more advanced. In addition to adopting the technique developed for surveying a meridian line, Ellicott took particular pains to ensure the accuracy of the measurements made by his surveyors. This extended to establishing a standard length for the foot. Even in Ellicott's time, there was no standard for the foot in the United States, and consequently the length of surveyors' chains varied appreciably. He dealt with this problem by constructing what was, in effect, his own standard, and used it to calibrate all of his chains.[ 25 ] In addition, Ellicott made certain that the compasses his surveyors used were adjusted so that meridians were based on true north rather than magnetic north, and he periodically checked their measurements by astronomical observations.[ 26 ]
During the years between 1784 and 1802, many other tracts of land, both large and small, were surveyed for the first time in northern, western, and central New York. The quality of these surveys varied considerably, but before they could be accepted they had to be approved by the Surveyor General, which gave De Witt some control over their quality. These surveys were filed in the Surveyor General's office, and provided more materials for the construction of De Witt's state map.
Many of these surveys are reflected in a preliminary map, which De Witt published in 1793 under the title 1st Sheet of De Witt's State-map of New York, seen here in Figure 4 [ 27 ].
Figure 4. Simeon De Witt, 1st Sheet of De Witt's State-map of New York (1793). New York State Library.
The title of this map shows clearly enough that it was intended as a first installment of his long-promised state map. It covers central New York from slightly east of Little Falls on the Mohawk River to the west side of Seneca Lake, and from the Pennsylvania line to Lake Ontario. It is partially based on the surveys of the New Military Tract done under De Witt's supervision, but it covers a much larger area. It includes, among other things, the colonial property holdings that De Witt had reconstructed around the headwaters of the Delaware and Susquehanna Rivers. Although it is primarily a property map, it includes hydrography, towns, and Indian reservations. This map would obviously have been useful to De Witt in his work as Surveyor General, as well as to anyone buying or selling property in central New York. The township divisions shown on this map were widely copied on other maps published in the final years of the eighteenth century. It is the first detailed and authoritative map covering a large part of central New York.
An interesting feature on De Witt's 1793 map is the north-south lines of the townships in the New Military Tract, which are depicted as running somewhat to the west of true north. This reflects De Witt's having had his surveyors run north-south lines without correcting for magnetic deviation of the compass. Although this practice was not unusual at the time (and also occurred in the federal rectangular surveys), we have seen that it contrasts with the practice of Andrew and Joseph Ellicott, who made a point of aligning their meridians with true north rather than magnetic north.
There is a good reason why De Witt's 1793 map covered this particular area. De Witt was in the peculiar situation of having better maps of the newly settled lands on New York's frontier than he did for the older areas, which had been surveyed haphazardly during colonial times. To remedy this problem, he even went so far as to place advertisements in newspapers calling for “those who wish to see lands in which they are interested laid down with the utmost accuracy, to furnish him for that purpose with such surveys as they may have in their possession, or be able to procure,” adding that “favors of the same kind from gentlemen who can produce maps of particular towns or other parts of the state, especially of the old settlements, with their improvements, will be thankfully acknowledged.”[ 28 ]
In another effort to gather information for his map, the legislature passed in 1796 a law requiring all town supervisors and county clerks to send to the Surveyor General's office maps of the areas under their jurisdictions.[ 29 ] Many of these manuscript maps have survived in the New York State Archives, and are themselves valuable sources of information about conditions at the local level in New York at the end of the eighteenth century. These maps sometimes contain details that cannot be found in any other source, but their quality is variable, and their surveying unreliable. De Witt himself remarked that some of the maps were “so erroneous as to be of little or no use.”[ 30 ]
De Witt somehow brought all of these diverse materials together to create his map of New York (Figure 1). Most of the map is at a scale of about 1:325,000, making it the first large-scale map of New York since Sauthier's Chorographical Map of 1779. The western portion of the state is shown in an inset at half-scale. The prime meridian passes through New York City (set at 74 degrees 03 minutes west of Greenwich).
A comparison of De Witt's map with that of Sauthier reveals the remarkable changes that had taken place in New York in the intervening twenty-five years. To begin with, there is much less white space on the De Witt map. As mentioned above, Sauthier's map does not show most of what is now central and western New York, which at the outbreak of the Revolution was still controlled by the Iroquois, and mostly closed to Euro-American settlement. On Sauthier's map, most of the area taken up by the Catskill and Adirondack Mountains, as well as the lowlands along the St. Lawrence River, are also shown as almost completely uninhabited. Thus, Sauthier's map faithfully reflects the extent of European settlement in New York on the eve of the Revolution, which still did not extend beyond Long Island, the Hudson River Valley, and the lower Mohawk Valley—along with the two narrow communication corridors from the Mohawk River to Oswego, and from Albany via Lake Champlain to Canada. Sauthier's map also shows Vermont as part of the Province of New York.
The state boundaries shown on De Witt's map are nearly identical with those of modern New York. In addition, a tremendous amount of detail is filled in. Most of the major lakes and rivers of the state are shown in nearly their correct positions. These features reflect the extensive surveying done by De Witt and others to establish the boundary with Pennsylvania, to lay out the New Military Tract in the Finger Lakes Area, and to survey the territories of the Holland Land Company and other land developers. Even the major lakes and rivers of the Adirondacks are located surprisingly well, and the outline of Long Island is shown much more accurately than on any previous map. On the other side of the ledger, in comparison with Sauthier, De Witt made only a perfunctory attempt to depict topography.
Both maps are works of collation, which combine information drawn from previous maps with information from new surveys. In the older areas of New York, De Witt copied extensively from pre-revolutionary maps, including Sauthier's Chorographical Map. But even in these areas, De Witt's map is vastly superior to Sauthier's in its depiction of roads and other details. None of this is surprising, since De Witt, because of his many years in office, was in a position to gather more information than Sauthier. The improvement of the outline of Long Island on De Witt's map is something of a puzzle, since I have been unable to uncover any evidence that a new survey was made of the island. But De Witt was remarkably conscientious. He even traveled around the state to check the accuracy of previous maps, and somehow he managed to put together a more accurate picture of the overall shape of Long Island.
A computer analysis (presented at the end of this article) shows clearly that overall the locations De Witt's map are much more accurate than on Sauthier's work.
Viewed in terms of engraving and printing, De Witt's map stands on pretty much the same level as that of Sauthier. The quality of the engraving and clarity of lettering on De Witt's map are not quite as good as on the best late eighteenth-century British maps, including Sauthier's, but are nonetheless quite respectable. Some observers think that De Witt's spare, legible style helped establish a new “distinctively American” type of map making.[ 31 ]
Predictably, there is a great deal of cadastral information on De Witt's map. Major estates and other land holdings are shown individually. In the area around the Mohawk River, De Witt still shows some holdings of pre-revolutionary land owners, including Sir William Johnson and George Croghan. However, De Witt's map includes much new information, such as town boundaries, which are carefully delineated. Most of the land in central and western New York is shown laid out in “townships.” Although there are some differences in the way the townships are depicted on De Witt's 1793 and 1803 maps, we again find those of heroic figures from Greek and Roman antiquity, many of whom still populate the landscape of upstate New York. Those who preferred their republican virtues in more abstract form might seek out their land in northern Herkimer and Lewis counties, where could be found the townships of Unanimity, Frugality, Perseverance, Sobriety, Economy, Regularity, Enterprise, and Industry. These townships belonged to “John Brown's Tract,” in the western Adirondacks near the modern town of Old Forge—an area that remains lightly settled even today.[ 32 ]
Although some of these townships existed on paper only, they illustrate the use of maps to impose on the land a fictive reality, which in some cases served to guide future developments. Although much of the state was still largely unpopulated, De Witt's map shows several (primitive but non-fictitious) roads going through western and central New York, along with such infant towns as Buffalo (then New Amsterdam), Geneva, Ithaca, Batavia, Bath, Cayuga, Seneca Falls, Plattsburgh, Utica, Massena. These and other towns were also named in an alphabetical list that accompanied the map. The magnitude of the changes in this area between the maps of Sauthier and De Witt is remarkable, even startling.
Particular attention should be paid to the depiction of Indian Reservations on De Witt's Map. By 1802, the vast land holdings of the Iroquois in western New York (still shown on Adlum's map) had been reduced to scattered reservations, which are depicted as basically empty and undeveloped. They are surrounded by the elaborate grid of townships with distinctly un-Indian names.[ 33 ]
There is an oddly visionary quality about De Witt's map, and particularly about the parts dealing with central and western New York. Although most of the roads, towns, and property boundaries shown actually existed, they were often embryonic at best, and (as is seen most clearly with townships like Enterprise and Frugality) some existed only on paper. Thus, his map was to some extent a planning document, which projected a vision of how De Witt and his colleagues thought the state should develop. To a remarkable extent, this vision was realized.
De Witt's map could not have been purchased by many people. It was advertised for $10 “pasted and colored” or $8.50 “in sheets.”[ 34 ] This was at a time when unskilled laborers earned less than one dollar per day, and skilled workers (such as carpenters or masons) were lucky to earn two dollars per day. It would be interesting to know exactly who did purchase De Witt's map, and how many copies were sold, but precise information is lacking. We can assume that it adorned the walls of some public offices, and those of wealthy land speculators and their agents. We know that the State Legislature distributed the map to other states, and De Witt implied that copies were sent to county clerks and town supervisors.[ 35 ] It was advertised extensively for a decade or so after its publication. Probably it was exhibited in some libraries, schools, and taverns—although direct evidence for this is lacking. By being displayed in such places, it most likely received greater public exposure than would be indicated by its price or sales. Directly or indirectly, it did much to create a kind of social consensus concerning the reality of De Witt's vision of New York State.
In 1804, De Witt published a reduced-scale “contraction” of his state map, as seen in Figure 5. [ 36 ] The engraving of the1804 map is somewhat careless, but it looks more like a modern map of New York State than his 1802 map, since all of it is at the same scale (ca. 1:950,000), and no part of the map is contained in an inset. The reason this map looks so familiar is that the outline of New York shown on this map, ungainly though it's shape may be, has become a kind of “logo” for the state. As such, it is instantly recognizable to most New Yorkers, and it appears on official and commercial publications that wish to associate themselves with the state. As noted above, the use of outline maps to represent and in some sense “make real” artificial political creations is widespread in post-Enlightenment cartography, and has been commented upon by a number of scholars.[ 37 ]
Figure 5. Simeon De Witt, Map of the State of New York (1804). Library of Congress.
Colored copies of this map were sold for two dollars, but apparently it was sold only by subscription.[ 38 ]. It does not seem to have been as widely distributed as its predecessor, although it appears to have been designed to reach a wider audience. It may be that De Witt's 1804 map was unable to find a niche in competition with other small-scale maps of the state, such as those of Samuel Lewis.[ 39 ]
A computer analysis of De Witt's maps shows that the latitudes and longitudes of individual locations throughout New York are remarkably accurate. This analysis was made using the program MapAnalyst, which was also used in my previously cited article on British colonial maps of New York. Details about this program can be found in that article (see Note 4). For the purposes of this analysis, I used the small-scale version of De Witt's map, which was published in 1804. The 1804 version is easier to work with, since it is all on the same scale, and western New York is not detached from the rest of the map.
The computer analysis revealed that De Witt's map is based on a conic projection. Figure 6 shows the magnitude of the displacements of specific locations on the De Witt 1804 map in comparison to a modern map. If one compares these displacements with those on Sauthier's map, the improvement is dramatic. Not surprisingly, De Witt is least accurate in the Adirondacks, which were virtually unsettled and poorly explored, although even here some of his locations are remarkably close to their modern coordinates. It is worth noting that De Witt's point locations for eastern Long Island are also somewhat less accurate than on the rest of his map. This is also not surprising given the lack of careful surveys made of this region in the colonial period, and De Witt's own work being focused primarily on upstate New York.
Figure 6. Computer Analysis of De Witt Map.
Accuracy is, of course, a relative matter. Although De Witt's coordinates are remarkably good by the standards of his time and in comparison with colonial maps, they are far from perfect by modern standards. Even outside of the Adirondack Region, his locations are often off by a mile or more from their correct latitude and longitude.
De Witt's maps had an extraordinarily far-reaching influence. Although De Witt's delineation of such things as roads, towns, and property boundaries rapidly went out of date, his overall depiction of New York's geography was not surpassed for decades. Between 1812 and 1828 mapmakers such as Amos Lay and John H. Eddy produced detailed maps of New York that updated the cultural information on De Witt's map.[ 40 ] The next major landmark in the mapping of New York State was David H. Burr's map and atlas of New York (1830), and Burr was a protégé of De Witt, who worked under his supervision in the final years of his long career as Surveyor General. In its overall depiction of the state, Burr's map and atlas improved little over De Witt's original map, although its atlas format permitted the inclusion of much more information about New York's counties, which were by then much more heavily populated and developed.[ 41 ]
Only in the second half of the nineteenth was there a significant advance over De Witt's methods, when maps of New York were finally made using the more “scientific” method of triangulation, and errors in the location of individual points were reduced to a matter of feet. Later maps, however, did not make basic changes in the image of the state created by De Witt and his contemporaries.