This layer is a georeferenced image of a map of the United States. The original map was published in 'A Complete Genealogical, Historical, Chronological, and Geographical Atlas; Being a General Guide to History, Both Ancient and Modern...' published by M. Carey in 1820. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, or other information associated with the principal map. A scanned version of this map was georeferenced by the Center for Spatial and Textual Analysis (CESTA) at Stanford University. This map is part of a selection of georeferenced historic maps from the David Rumsey Map Collection at Stanford University. This layer provides an historical perspective of the cultural and physical landscape during this time period. The wide range of information provided on these maps make them useful in the study of historic geography. As this map has been georeferenced, it also can be used as a background layer in conjunction with other GIS data. The horizontal positional accuracy of a raster image is approximately the same as the accuracy of the published source map. The lack of a greater accuracy is largely the result of the inaccuracies with the original measurements and possible distortions in the original paper map document. There may also be errors introduced during the digitizing and georeferencing process. In most cases, however, errors in the raster image are small compared with sources of error in the original map graphic. The RMS error for this map is 221.645 meters. This value describes how consistent the transformation is between the different control points (links). The RMS error is only an assessment of the accuracy of the transformation.
