Illinois National Aerial Photography Program (NAPP) Digital Orthophotography quarter Quadrangle (DOQ) data have been created for 102 counties in the Universal Transverse Mercator (UTM) coordinate system with a NAD83 datum. Data were created using USGS NAPP specifications using black and white film during the leaf-off periods of spring, 1998, 1998, 2000, and 2001 at a 1 meter by 1 meter resolution.FileengIllinois Geospatial Data ClearinghousePublic1998 - 2001 Illinois Digital Orthophoto Quadrangle (DOQ) Data [Illinois]Datasets1998-2001