The U.S. Geological Survey 1:24,000-Scale (7.5 minute) Orthophotoquads collection contains orthophotoquads at a scale of 1:24,000 (7.5 minute series). These orthophotomaps have been created from individual aerial photos in a photogrammetric process to remove distortion to produce an ortho image and use the legacy North American Datum of 1927 (NAD27) for the coordinates shown on each sheet. As a result, these coordinates must be converted to the current North American Datum of 1983 (NAD83) or the World Geodetic System of 1984 (WGS84) for use with modern maps and GPS/GNSS devices. The coordinates shown in the Resource Details (Footprint Polygon field) and the Location Data (map) sections for each photomap are in the NAD27 datum, until they can be converted to the NAD83 datum.
