Flights flown between July 4, 1938 and September 21, 1938 by Iowa Aerial Surveys, Inc., for the U. S. Dept. of Agriculture, Agricultural Adjustment Administration. Photos numbered BGD-1-1 through BGD-6-3. Scale not given. Stereoscopic coverage. Only indexes are georeferenced.
Clay County (Ill.) (W 88°42′--W 88°15′/N 38°55′--N 38°36′)
Illinois State Geological Survey
280 remote-sensing images, 1.47 gigabytes, average file 5.37 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.