McMurdo Station became the center of scientific and logistical operation during the International Geophysical Year, an international scientific effort that lasted from July 1, 1957, to December 31, 1958. The Antarctic Treaty, subsequently signed by over forty-five governments, regulates intergovernmental relations with respect to Antarctica and governs the conduct of daily life at McMurdo for United States Antarctic Program (USAP) participants. The Antarctic Treaty and related agreements, collectively called the "Antarctic Treaty System" (ATS), opened for signature on December 1, 1959, and officially entered into force on June 23, 1961.