Andrew W. Mellon expertly invested money into multiple industrial and financial ventures including steel, aluminum, coal, utilities, railroads, banks, and more. Developed his father’s bank into Mellon National Bank which aided in the transformation of Pittsburgh into an industrial giant. Mellon Institute for Industrial Research was created by A.W. and brother Richard in 1909 in an effort to fund research in promotion of better business and scientific practices. A private man who kept his early philanthropy quiet, like canceling small debts for Christmas and purchasing food and clothing for people in Pittsburgh.
Named Secretary of the Treasury in 1921 and served as Secretary for Presidents Harding, Coolidge, and Hoover, cutting the national debt with what was known as the "Mellon Plan" and authored the book Taxation: The People’s Business. Resigned in 1932 and accepted the position of U.S. Ambassador to Great Britain for one year.
After retirement, began his largest philanthropic quest, the National Gallery of Art in Washington, DC. Collected works while Secretary but solidified his plans with the A.W. Mellon Educational and Charitable Trust in 1930. Following the announcement of the Gallery, personal collection neared 350 pieces from which 121 paintings and twenty-one sculptures were added to the Gallery collection. Also established a trust to fund the Gallery, donating $10 million, as well as giving an estimated $21 million in art and $15 million for the construction of the Gallery building.The grand opening occurred in 1941 after his death.
The legacy of A.W. Mellon remains with the Andrew W. Mellon Foundation philanthropic trust formed in 1969 through the merger of the Avalon Foundation (est. 1940 by Ailsa Mellon Bruce) and the Old Dominion Foundation (est. 1941 by Paul Mellon). Prior to the merger, the Avalon Foundation distributed funds to hospitals and health agencies, educational institutions, and cultural programs including the Metropolitan Opera and the New York Philharmonic. The Old Dominion Fund concentrated on the humanities and liberal education. The merged foundation, with assets of $3.4 billion (1998), continues to support the areas of health, education and the humanities and has added programs in conservation, public affairs and population studies.