Aerial photography became an important part of the mapmaking process in the twentiethth century. Aerial photographs provide a straightforward depiction of the physical and cultural landscape of an area at a given time. When skillfully interpreted, these aerial images supply geographers, historians, ecologists, geologists, urban planners, archaeologists, and other professionals with a pictorial basis often critical to their studies. Increasingly, members of the legal profession have used aerial photography in the settlement of cases involving property disputes, riparian rights, and transportation rights-of-way. Recently, genealogists have used aerial photography to identify and locate ancestral sites.
The federal government became significantly involved in the systematic acquisition of aerial photography in the 1930's. Until that time, no comprehensive collection of aerial imagery of the United States existed. The Department of Agriculture, given the responsibility for crop determination and soil erosion, created many of the earliest aerial coverages. The result was an extensive collection of vertical (mapping) aerial imagery covering approximately 90 percent of the contiguous United States. This large-scale aerial photography, which was taken between 1935 and 1954, forms a unique collection within the millions of aerial photographic images held by the Cartographic and Architectural Section. Because one of the best ways to exploit aerial photography in research is through comparison of images from various dates, the Section has accessioned an extensive collection of military-flown imagery of the United States dating from about 1940 to 1960. This collection provides coverages of Alaska and Hawaii as well as most of the contiguous United States.
World War II brought a rapid acceleration in the use of aerial photography of foreign areas for both military operations and mapping purposes. The Section holds World War II aerial images covering parts of the European, Mediterranean, and Pacific Theaters of Operation, taken by units of the U.S. and Allied Air Forces. Included are both vertical mapping photography and oblique reconnaissance photography. The Section also holds approximately 1.2 million prints of aerial photographs taken by the Germany military. Coverages are widespread--Europe (from the British Isles to the Ural Mountains), the Middle East, and North Africa are included in this collection. Many of the prints are annotated to indicate military installations and defenses; other prints are marked to show potential bombing targets. While the scale and quality of the photographs in this collection vary considerably, the imagery provides unique wartime coverages of many of the contested areas. A smaller collection (about 37,000 images), taken by the Japanese military between about 1933 and 1945, consists of aerial photography of parts of China, Southeast Asia, and the Pacific Islands. The Section also maintains custody of satellite photographs for 1960-1972 from the CORONA project--the United States first satellite reconnaissance program.