Gilroy was born in
Sligo,
Ireland, and immigrated with his parents to
New York City at age seven. His father died soon afterwards, and he left school at age 16 to begin working in the publishing business, where he eventually became a
proofreader. He later served as a court clerk, and Deputy County Clerk and Undersheriff for
New York County. Active in the
Democratic Party, from his early 20s he was a key member of the
Tammany Hall organization, beginning as a messenger for "Boss"
William Tweed, and serving as confidential secretary for
Henry W. Genet, Tweed's Tammany Hall successor. In 1889, Gilroy managed the successful mayoral campaign of
Hugh J. Grant, and as a reward was appointed Commissioner of Public Works, a post he held from 1889 to 1893. From 1890 to 1892, Gilroy was the titular head of Tammany Hall, the organization's Grand Sachem. In fact, the boss of the organization continued to be
Richard Croker, who was the organization's unofficial leader from 1886 to 1902. In 1893 Gilroy succeeded Grant as Mayor. His administration was largely defined by the 1894
Lexow Investigation, which uncovered widespread police department corruption that was directly linked to Tammany. Gilroy did not run for reelection, and was succeeded in 1895 by reform candidate
William L. Strong, who ran with the backing of
Republicans and anti-Tammany Democrats. Gilroy was a Delegate to the
1896 Democratic National Convention. Afterwards, he withdrew from politics, and served as President of the Twelfth Ward Bank until retiring in 1901. ==Family==