Flights flown between May 6, 1939 and August 9, 1939 by Iowa Aerial Surveys, Inc., for the U. S. Dept. of Agriculture, Agricultural Adjustment Administration. Photos numbered BGG-1-25 through BGG-5-53. Scale not given. Stereoscopic coverage. Only indexes are georeferenced.
Crawford County (Ill.) (W 87°57′--W 87°31′/N 39°10′--N 38°51′)
Illinois State Geological Survey
235 remote-sensing images, 1.49 gigabytes, average file 6.47 megabytes
Scanned from 7 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 6:1. Uncompressed TIFF images on cd available from the Illinois State Library Map Dept.