The Third Byrd Antarctic Expedition, also called the United States Antarctic Service Expedition, took place from 1939-1941. This expedition established two base camps 1600 miles apart. West Base was near the former Little America base (68° 29' S, 163° 57' W) and East Base was near the Antarctic Peninsula on Stonington Island (68° 12' S, 67° 03' W). Exploration flights out of these two bases led to the discovery of most of the Marie Byrd Land Volcanic Province (e.g. Executive Committee Range) and much of the coastal region including the Walgreen, Hobbs, and Ruppert Coasts. During the expedition trail parties from West Base visited the northern Ford Ranges and south slopes of the Fosdick Mountains.