After her husband's death in 1909, Harriman continued to manage her considerable empire, valued between $70 and $100 million (). As one commentator noted, her "lifelong interest in philanthropy was about to become a profession." One of her first undertakings was to fulfill E.H.'s vision of an immense state park. In 1910, Mary donated of the Arden estate to the State of New York, leading to the creation of
Harriman State Park as an extension of the Palisades Interstate Park, along with the $1 million () endowment for its management. She made it conditional upon others contributing $1.5 million () and the State of New York matching these funds with an added $2.5 million (). She received the
National Institute of Social Sciences Gold Medal in 1925 and the
Pugsley Gold Medal in 1929 "...for her services in the establishment of the
Palisades Interstate Park." This was to be the start of a life dedicated to philanthropy. Monies were contributed to The Boys' Club of New York that E.H. loved and supported, to the
American Red Cross, to
John Muir to help save the
Yosemite Valley and to
Yale University for an endowed chair of Forestry. She also supported a number of artists, including especially sculptor
Malvina Hoffman, whose bust of Harriman is still on display in Arden House. In her married years Harriman was a strong, silent, and supportive wife. After her husband's death, she became a leader in American philanthropy, donating her personal and private resources to improve the world around her. As part of this philanthropy, she gave over a half-million dollars to the
Eugenics Record Office, an organisation which promoted racist, unethical and discriminatory policies such as forced sterilisation of racially or medically "inferior" people, upon the encouragement of her friend
David Starr Jordan. In 1913, she created the
E. H. Harriman Award in her late husband's honor to recognize outstanding achievements in railway safety; the award is still presented on an annual basis today. ==Personal life==