McAdoo was a leader of the Progressive movement and played a major role in the administration of his father-in-law President Woodrow Wilson.

He gained fame as the president of the Hudson and Manhattan Railroad Company and served as the vice chairman of the Democratic National Committee.

McAdoo presided over the establishment of the Federal Reserve System and helped prevent an economic crisis after the outbreak of World War I.

McAdoo's second marriage ended in divorce in July 1935, and he married a third time at nearly 72, to 26 year old nurse Doris Isabel Cross (1909–2005), in September 1935.

McAdoo offered to resign after his wedding, but President Wilson urged him to complete his work of turning the Federal Reserve System into an operational central bank.

As head of the Department of the Treasury, McAdoo confronted a major financial crisis on the eve and at the outbreak of World War I, in July and August 1914.

Many of these foreign investors then converted their dollars into gold, as was common practice in international monetary transactions at the time, in order to repatriate their holdings back to Europe.

As a result, the treasuries of those countries more quickly exhausted all of their net foreign exchange holdings (those that were on hand and in their possession before McAdoo closed the markets), currency, and gold reserves.

[15] McAdoo's bold stroke, Silber writes, averted an immediate panic and collapse of the American financial and stock markets.

More than this, McAdoo's actions both saved the American economy and its future allies from economic defeat in the early stages of the war.

In order to prevent a replay of the bank suspensions that plagued America during the Panic of 1907, McAdoo also invoked the emergency-currency provisions of the 1908 Aldrich–Vreeland Act.

Silber credits his actions for having turned America into a world financial power, in his book When Washington Shut Down Wall Street.

During his tenure as Secretary, he broke with long-standing policy and ordered implementation of Jim Crow in all Treasury facilities, even in the north where they had previously not existed.

[16] McAdoo told reporter Oswald Garrison Villard that racial segregation was needed in the Treasury to prevent friction.

McAdoo ran twice for the Democratic nomination for president, losing to James M. Cox in 1920,[18] and to John W. Davis in 1924,[19] even though in both years he led on the first ballot.

[23] A committed Prohibition supporter, McAdoo's first presidential bid was scuttled by the New York state delegation and other Northern opponents of the banning of alcohol at the 1920 Democratic National Convention.

Widely regarded as the front-runner in 1923, McAdoo's candidacy was badly hurt by the revelation that he had previously accepted a $25,000 contribution from Edward L. Doheny, an oil tycoon implicated in 1922 in the Teapot Dome scandal.

[26] McAdoo had returned the normal-course contribution once he learned of Doheny's possible bribes to Secretary of the Interior Albert Fall to get oil leases.

McAdoo defeated Oscar Underwood, who was an opponent of the Ku Klux Klan and Prohibition, in the Georgia primary and split the Alabama delegation.

In February 1923, McAdoo and a consortium of eastern investors attempted to establish the first city bus service in Los Angeles.

[35][36] McAdoo died on February 1, 1941, of a heart attack while traveling in Washington, D.C., after the third inauguration of Franklin D. Roosevelt,[37] and was buried in Arlington National Cemetery in Virginia.

In the 1920s, as his Democratic Party polarized, he took the side of rural America, especially the South, as opposed to Al Smith's big cities.

He is a significant character in the Glen David Gold novel Sunnyside, encouraging Charlie Chaplin to help with efforts to raise funds for World War I before advising him on the formation of United Artists.

"[43] And in reference to Warren Harding, McAdoo said his public utterances were "an army of pompous phrases moving over the landscape in search of an idea.