Mapping Then and Now

Map of Lewis and Clark's Track, Across the Western Portion of North America

These two images show the original map, and then the georeferenced map image that resulted when the map was brought into correct geographical space. Over 60 reference points were used to correct the map. The original expedition map was amazingly accurate nonetheless, given the survey tools available to Lewis and Clark at the time the map was made. The curving nature of the georeferenced map image gives a good sense of some of the errors in the original map and its projection.