Irrigation map of the United States / engraved and printed by the U.S. Geological Survey ; outline of irrigated areas based upon data collected by the Bureau of the Census, 1910 ; revised by Irrigation Division, Office of Experimental Stations, and by theUnited States. Office of Farm Management1915"Jan. 1, 1915" in lower left margin.Irrigated areas shown on outline map of the United States. Explanation in margin.This edition has county names printed in blue.cartographic