Flights flown between July 27, 1939 and August 27, 1939 by Midwest Aerial Surveys, Inc., for the U. S. Dept. of Agriculture, Agricultural Adjustment Administration. Photos numbered BWY-1-1 through BWV-5-37. Scale not given. Stereoscopic coverage. Only indexes are georeferenced.
LaSalle County (Ill.) (W 89°10′--W 88°35′/N 41°38′--N 40°55′)
Illinois State Geological Survey
587 remote-sensing images, 2.01 gigabytes, average file 3.5 megabytes
Scanned from 9 x 9 contact prints (nominal scale ca. 1:20,000) on Crosfield 646IE 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.