United States. Department of AgricultureNitrate Base; By USDA-AAA (BOI-186-132,133); Scale 1:20,800JPEGoai:digital.library.illinois.edu:ebd198a0-8a10-0137-6d99-02d0d7bfd6e4-5122engPublicStereogram No. 122 - DeaconImagerySouth Dakota--Pennington CountySouth Dakota1938-10-24University of Illinois Urbana-Champaign