Authoritative GeoChange U.S. Topos (Copyright) The last edition of 7.5 x 7.5 minute paper topographic maps of the USGS have been hyper-accurately imaged, processed, georeferenced, and colorized. These topos have been draped onto NAIP aerial images (accurate to ca. 5 m). Because of high quality USGS cartography, and because of The W.E. Upjohn Center's thorough accuracy control, these maps may often be used to a 16,000 scale (1 in = 500 ft). Where no map content exists, users see the NAIP aerial image displayed with no overlay. Where map content exists, users see the topo and the NAIP, both semi-transparently. You can assess geographic change by comparing the foreground map with the background image in this hybrid map. The background complements the foreground for ease of user interpretation, and vice versa. Seeing both displays helps the user to better understand this place as it is now.