(CNN) Monday marked a historic day in Chicago as the city inaugurated its first African-American lesbian mayor.
Lori Lightfoot, a former assistant US attorney, was sworn in at Wintrust Arena in the Near South Side community.
"We are a proud city with a proud history," Lightfoot said. "In this moment, I can't help but look at all of you and think about what lies ahead and what we can be together."
She said she would fight the city's gun violence problem, pledged job growth and promised to hold equity and inclusion as a guiding principle. Lightfoot said she would push for integrity in city government.
"Putting Chicago government and integrity in the same sentence sometimes may seem a little strange," she said. "But friends, that's going to change, because it's got to change. For years, they've said, 'Chicago ain't ready for reform.' Well, get ready because reform is here."
Lightfoot, 56, defeated Toni Preckwinkle, a political insider who heads the Cook County Board and chairs the Cook County Democratic Party, in a runoff election in April. Preckwinkle is also an African-American woman.
Lightfoot and Preckwinkle were the final two contenders in a crowded field of 14 candidates vying to be mayor of the country's third-largest city.
The inauguration included performances by Miguel Cervantes of Chicago's "Hamilton" and the Chicago Gay Men's Chorus, among others. Lightfoot thanked outgoing Mayor Rahm Emanuel, who has led Chicago since 2011 and decided not to run for a third term.
"I thank Mayor Emanuel for his dedication to service to this city, which was exemplified by the attention and time he and his staff devoted to making this transition as smooth as possible," she said.
Lightfoot takes office amid efforts to address violent crime in the city and improve police-community relations.
Violent crime totals in Chicago have made headlines in recent years. In 2016, the city reported its highest number of homicides in two decades: 762. But killings have dropped since then: 650 in 2017 and 550 in 2018, police said.
The Chicago Police Department has credited the drop in violence partly to hiring more officers and stronger community policing. The department added 1,161 officers in two years, exceeding a 2016 pledge made by Mayor Emanuel and police Superintendent Eddie Johnson to add 970.
Still, a series of high-profile cases have strained police-community relations. In the wake of the Laquan McDonald scandal -- in which a white police officer, Jason Van Dyke, shot a black teenager 16 times as he walked away from police -- Lightfoot was appointed by Emanuel to head the newly created police accountability task force.
Many of the panel's recommendations were similar to the findings in the US Justice Department report that found serious problems with the police department's handling of racism within its ranks. Under Lightfoot, the city replaced its widely criticized police oversight agency with a civilian body designed to have much more oversight over officers and their supervisors.
She made holding police officers accountable for their actions a bedrock of her campaign.
Lightfoot's platform also looked at investing in neighborhood schools, according to her website. She promised to create an elected and representative school board so parents and the community can have a voice in how the school system operates.
The new mayor also promised to expand affordable housing options and support small businesses.
Lightfoot's election marks her first time in political office.
She was born and raised in Ohio and comes from modest beginnings. Her mother worked as a health care aide. Her father worked in a factory and as a janitor.
Lightfoot went to college at the University of Michigan. After two years as a legislative aide in Washington, she attended law school at the University of Chicago. She has lived in the city for all but one year since 1986.
She often brings up her own background while promising to improve the city's school system and bridge the economic gap between city neighborhoods.
"I want to make sure that kids who look like me and are growing up in families like mine have the opportunity at their fingertips," she said.
Lightfoot describes herself as "an out and proud black lesbian." She and her spouse, Amy Eshleman, have a 10-year-old daughter.
Lightfoot joins a shortlist of black women mayors to lead a US city with a population of at least 100,000 people. Including her, there are only 13.