As a teenager, he worked on his family's farm, selling milk and garden produce to his neighbors, and served as a paper boy for his local newspaper, The Sun Chronicle.

[6] While attending Attleboro High School, Hagerty played as the only boy on the all-girls field hockey team his senior year before graduating in 1987.

[16][17] His status on the ballot was briefly threatened by an objection from a supporter of Mayoral candidate Brian Miller, who claimed Hagerty's petitions did not cite the correct date of the election.

[23] Hagerty was endorsed by all living preceding mayors of Evanston: Tisdahl, Lorraine Morton, and Jay Lytle, as well as and Cook County Commissioner Larry Suffredin.

[28] In the Mayoral primary on February 28, 2017, Hagerty received 44.4% of the vote, advancing him to a runoff election facing sixth ward Alderman Mark Tendam, who won 20.5%.

[40] This was due in part to Hagerty and the council's emphasis on transit-oriented design, adding 1,000 new housing units to Evanston and 3,624 new residents according to the 2020 census results,[41] all in a state with a declining population.

[42] Major new commercial developments included Centrum Evanston, Noyes Loft, The Link, Albion, 601 Davis, 1727 Oak Ave, and 1815 Ridge.

[43] Additional community amenities included Out of Space Concert Series,[44] Downtown Target,[45] Evanston's first Pridefest,[46] Theo Ubique Theater,[47] and many new breweries[48] and stores.

[55] Hagerty approved and the City constructed the award-winning[56] $53M Robert Crown multi-use community center,[57] which included a library, early childhood program, two ice rinks, a multi-sport gymnasium, and turf fields; the award-winning[58] $6M modern redesign[59] and renovation of Fountain Square; the award-winning redesign[60] of Chicago Avenue and Sheridan Road adopting a complete street[61] approach to more safely accommodate bikers, pedestrians, public transportation, and vehicles; and the interior renovation[62] of the Fleetwood-Jourdain Community Center, located in the heart of the Fifth Ward, Evanston's historically Black center, allocating funds from Northwestern's Good Neighbor Fund.

[66] Hagerty expanded the Youth & Young Adult Division to focus on workforce development opportunities through the creation of the Mayor's Employers Advisory Council (MEAC[67]) partnership.

[75][76] Former President Obama praised Evanston for its collaborative efforts to develop recommendations to change the city's use of force policy and improve training and accountability standards.

[86] Throughout the pandemic, Hagerty communicated extensively[87] with residents, held Coronavirus Q&A sessions,[88] and preached a whole of community[89] effort to the city's response and recovery.

Despite his active involvement in the response and recovery effort, Hagerty was criticized for getting vaccinated in late January 2020 because some believed he did not qualify as an essential worker.

Hagerty directly allocated $4 million in good neighbor funds to infrastructure, human services, and public safety projects during his four-year term.

[98] Hagerty supported and signed the nation's first reparations fund, allocating $10M of the city's new cannabis revenue to be specifically invested into the Evanston Black community.

Hagerty also established the city's first pilot guaranteed income program directly allocating money from the Northwestern Good Neighbor Fund.

[138] Within hours, a petition was circulated to revoke Blake Peters Day, criticizing Hagerty for recognizing something as trivial as a basketball player's shot.

[139] Soon thereafter, Hagerty learned that the Clerk released private information of juveniles involved in police incidents and a female resident's sexual assault allegation to the public.

[140][141] Hagerty and the council, under Alderman Don Wilson's leadership, passed a measure temporarily taking down the public FOIA system, Next Request, in order to protect the privacy of residents.

[151] In August 2019, Clerk Reid withdrew his lawsuit claiming that the council's move to add additional FOIA Officers, including one from the Police Department, removed his standing.

Soon after the vote to censure the city clerk, the highly confidential executive session report describing the details of his misconduct and the employees who filed the complaints, plus concerns of him recording conversations with others without their knowledge, including two aldermen, was released to the media.

[164][165] The mayor expressed outrage that someone on the council or in the city manager's office would violate laws established to protect the privacy of employees and the confidentiality of discussions in executive session.

[171] The city clerk subsequently conducted an interview with WGN referring to Hagerty's "Trumpian" ways in calling for an investigation of this leaked report.

[174][175] Hagerty was accused by Reid and his supporters of racism and badgering when he repeatedly inquired where approximately a dozen missing executive session recordings and meeting minutes were.

[208][209] Hagerty issued a public letter to President Shapiro within 24 hours stating that both police and protesters deserve to do their jobs peacefully, and when that doesn't occur, arrests will be made.

[235] Wanting to bring attention to the importance of preventative care, especially during the pandemic, Hagerty chose to have a colonoscopy rather than attend the City Council meeting on December 14, 2020.

[239] Four hours into the first day of the two-day street festival, protesters arrived at the fair and took to social media claiming that the vehicle was deployed by Homeland Security to round up undocumented immigrants.

[240] Hagerty issued a statement via the City claiming the vehicle was there to protect fairgoers and to serve as a command center should there be any public safety incidents.

[242] Asked in his final state of the City address to reflect on his favorite moment as Mayor, Hagerty described the opportunity his 10-year-old son had to meet Joe Biden at Northwestern University, who gave him a command coin and a few dollars to buy an ice cream.

During the campaign, Biss accused a local PAC, Evanston Together, of using "dark money" to advocate for certain candidates who supported a City Manager form of government.