Flights flown between August 18, 1938 and October 21, 1938 by Iowa Aerial Surveys, Inc., for the U. S. Dept. of Agriculture, Agricultural Adjustment Administration. Photos numbered BHF-1-5 through BHF-3-14. Scale not given. Stereoscopic coverage. Only indexes are georeferenced.
Union County (Ill.) (W 89°31′--W 89°03′/N 37°36′--N 37°20′)
Illinois State Geological Survey
241 remote-sensing images, 880 megabytes, average file 3.7 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.