Iowa. State Planning Board. Committee on Land UtilizationNegative. "Iowa state plan." "Project no. 1030." "1030-21."1 map : black line ; 84 x 114 cmJPEG2000730945453; MAPG4151_J6_193_I6.jp2islandora: testiadep_1813https://digital.lib.uiowa.edu/node/422924engUniversity of Northern IowaPublicRecommended crop changes: Iowa: recommended changes in acreage in corn, small grain, hay, pasture, by districtsMapsIowa1930-1940University of Iowa