American Geophysical Union  The American Geophysical Union (AGU) is a 501(c)(3) nonprofit organization of Earth, atmospheric, ocean, hydrologic, space, and planetary scientists, consisting of over 62,000 members from 144 countries. AGU's activities are focused on the organization and dissemination of scientific information in the interdisciplinary and international fields within the Earth and space sciences. The geophysical sciences involve four fundamental areas: atmospheric and ocean sciences; solid-Earth sciences; hydrologic sciences; and space sciences. The organization's headquarters is located on Florida Avenue in Washington, D.C. The AGU was established in December 1919 by the National Research Council (NRC) to represent the United States in the International Union of Geodesy and Geophysics (IUGG), and its first chairman was William Bowie of the United States Coast and Geodetic Survey (USCGS). For more than 50 years, it operated as an unincorporated affiliate of the National Academy of Sciences. On June 29, 1972, AGU was incorporated in the District of Columbia and membership was opened to scientists and students worldwide. The AGU was intended to promote "pure" geophysics; exploration geophysics has its own society, the Society of Exploration Geophysicists. In a March 1919 report by a committee chaired by Robert S. Woodward of the Carnegie Institution, geophysics was defined as a collection of "borderlands" (closely related, mutually dependent subjects): astronomy, geodesy, geology, meteorology, oceanography, seismology, terrestrial magnetism, terrestrial electricity, tides, and volcanology. The AGU was organized under seven sections: Geodesy, Seismology, Meteorology, Terrestrial magnetism and electricity, Oceanography, Volcanology, and Geophysical chemistry. Hydrology was added in 1930 and Tectonophysics in 1940. In suggesting the latter name, Norman Bowen evoked a familiar theme: to "designate this new borderline field between geophysics, physics and geology ... for the solution of problems of tectonics." The first meeting of the AGU took place on April 23, 1920. In attendance were 25 members. Up to 1930, the number of members was restricted and members were elected. In 1932 the first annual dues of were imposed. The membership grew to 4600 in 1950; 13,000 in 1980; and 26,000 in 1990. As of 2018, it had 62,000 members from 137 countries.