Flights flown between November 14, 1938 and April 13, 1939 by Holmberg Aerial Survey Co., for the U. S. Dept. of Agriculture, Agricultural Adjustment Administration. Photos numbered BWQ-1-1 through BWQ-10-71. Scale not given. Stereoscopic coverage. Only indexes are georeferenced.
Cook County (Ill.) (W 88°16′--W 87°31′/N 42°09′--N 41°27′)
Illinois State Geological Survey
691 remote-sensing images, 1.92 gigabytes, average file 2.9 megabytes
Scanned from 7 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.