In 1917 with the consent of Tammany and William Randolph Hearst, he was put forward as a Brooklyn Democratic candidate for Mayor and won the first of two terms.

By the end of his second term, however, a report by a committee appointed by Governor Al Smith severely criticized his administration's handling of the subway system.

After his term as mayor, Hylan spent much time attacking the "interests," arguing that industrial concentration gave great power to individuals to influence politics and impoverish the working poor.

Hylan's mother, who came from the Jones family upstate,[3] had a Welsh father and a maternal grandfather, Jacob Gadron, who fought in the American Revolution among Lafayette's forces.

[b] He fondly remembered her throughout his life and wrote that the words she spoke on leaving the family ("Be honest, be truthful, be upright, and do by others as you would have them do unto you") were "indelibly imprinted on" his memory.

Farm work came first, the school district was impoverished, and only one family could afford the required grammar or history book, which Hylan occasionally borrowed.

[6] In his teenage years, Hylan made extra money to help pay the mortgage interest by working each spring for the Catskill railroad, digging earth and tamping it beneath the tracks to stabilize them after the effects of winter weather.

He got into law school with the help of his wife, as well as that of a teacher who gave up his lunch hour to help, and for whom Hylan later found a position in the Department of Water Supply, Gas and Electricity when he became mayor.

[17] The firm occasionally received positive local publicity, such as the time when they obtained a ruling that the Brooklyn Heights Railroad Company had to offer free transfers at all junctions.

In addition to his union membership, which he kept up even when he was mayor,[13] he was a member of the Foresters of America, the Broadway Board of Trade, the Twenty-eighth Ward Taxpayer Association,[22] and he began working his way up the local Democratic club.

[24] Some observers believed that it was Murphy's intention, despite the risk of lost votes in Brooklyn, as long as he could cut off the Kings County party's independent base of patronage.

At the City Committee meeting on September 18, party leaders from Queens, the Bronx and Richmond joined Brooklyn in expressing their concern.

[24] At the Democratic City Committee meeting on September 24, Murphy defied Brooklyn leaders to take the fight over McClellan to the Convention the next week, knowing that Tammany controlled a majority of the delegates.

[30] With a view to sowing confusion among the Fusionists, Murphy without consultation outside of Tammany proposed adding two Fusion candidates to the ticket—Edward M. Grout for Controller and Charles V. Fornes for President of the Board of Aldermen.

Brooklyn Assistant District Attorney Martin W. Littleton led the charge, looking directly at Murphy in front of him and delivering a blistering speech scoring Tammany "treachery" for selecting Democratic "traitor" Grout.

While the Kings County delegation under the leadership of state senator Patrick H. McCarren made show of unity by moving the unanimous nomination of McClellan when its nominee was defeated, a similar motion for Grout and Fornes, however, was "howled down.

"[35] The next day at the Brooklyn Democratic headquarters in the auction room on Willoughby Street, all talk of McLaughlin's plan for an opposition ticket to Tammany's had ceased.

Hylan defeated the reformer John Purroy Mitchel in the four-sided 1917 mayoral election, restoring the power of Tammany at City Hall.

On December 30, 1925, Hylan resigned from office one day before the end of his term in order to assure his eligibility for a $4,205 annual pension from the city.

According to Robert Moses, Hylan went through most of a mayoral campaign using just one stump speech: a call to keep the five-cent subway fare in place.

They use the columns of these papers to club into submission or drive out of office public officials who refuse to do the bidding of the powerful corrupt cliques which compose the invisible government.

It operates under cover of a self-created screen [and] seizes our executive officers, legislative bodies, schools, courts, newspapers and every agency created for the public protection.Hylan died of a heart attack at the age of 67 on January 12, 1936, at his home in Forest Hills, Queens.