The name McAdoo surfaced in the U.S. baby name data in the 1910s:
1919: 12 baby boys named Mcadoo
1918: 26 baby boys named Mcadoo [peak usage]
1917: 11 baby boys named Mcadoo [debut]
The Social Security Death Index (SSDI) data shows a similar pattern of usage:
1919: 11 people with the first name Mcadoo
1918: 24 people with the first name Mcadoo
1917: 6 people with the first name Mcadoo
1916: no people with the first name Mcadoo
1915: 2 people with the first name Mcadoo
What was drawing attention to the Irish surname McAdoo at that time?
Businessman and politician William Gibbs McAdoo (1863-1941), who served as Secretary of the Treasury from 1913 to 1918 under Woodrow Wilson (who, incidentally, was his father-in-law). McAdoo became relatively famous during WWI:
[A]s chair of the War Finance Corporation, he basically set up the policy for how to fund World War I by raising taxes and instituting gold savings bonds called “Liberty Loans,” a money-raising and propaganda tool. When German submarine attacks made transatlantic trade dangerous and expensive, he created the U.S. Shipping Board in 1916. And he served as director general of U.S. railroads when the government started controlling the railroads to make sure military supplies and personnel got transported in a timely manner … [P]eople thought so highly of McAdoo at the time that they equated him to Alexander Hamilton, the nation’s first Secretary of the Treasury. TIME summed up his accomplishments in 1932 by quoting a jingle: “He’s always up and McAdooing / From Sun to Star and Star to Sun / His work is never McAdone.”
William G. McAdoo also campaigned for the Democratic presidential nomination twice, in 1920 and 1924, but lost both times. (The surname’s final appearance in the baby name data was 1924, in fact.)
Here are several interesting examples of “McAdoo” being used as either a first or a middle name:
Please note that I did include names in the gray area between one syllable and two syllables. The deciding factor on these particular names (such as Charles, Miles, and Noel) will be your own interpretation/accent, so be sure to test the names out loud before making any final decisions.