Flights flown between September 27, 1938 and May 30, 1939 by Iowa Aerial Surveys, Inc., for the U. S. Dept. of Agriculture, Agricultural Adjustment Administration. Photos numbered BGX-1-2 through BGX-5-97. Scale not given. Stereoscopic coverage. Only indexes are georeferenced.
Montgomery County (Ill.) / W0894200-W0890800 / N0393200-N0390000
Illinois State Geological Survey
332 remote-sensing images, 2.03 gigabytes, average file 6.26 megabytes
Scanned from 9 x 9 contact prints (nominal scale ca. 1:20,000) on Crosfield Celsis 6200 drum scanning system at 750 dpi. Quality assurance target not published but available by contacting the Illinois State Library Map Dept. MrSID files compressed at a target ratio of 12:1. Uncompressed TIFF images on cd available from the Illinois State Library Map Dept.
Mode of access: World Wide Web. System requirements: Plug-in or image viewer, ExpressView Browser plug-in available for download. System requirements for interactive map: Google Chrome best.