Chicago will swear in its first black female and first openly gay mayor Monday, concluding Lori Lightfoot’s astonishing, yearlong rise from near anonymity to leader of the nation’s third-largest city.

Lightfoot defeated Cook County Board President Toni Preckwinkle in a landslide runoff election April 2, claiming 73% of the vote and winning all 50 wards. She also won a majority of the white vote, the black vote and the Latino vote.

“We are going to transform our city,” Lightfoot said last week. “No one person, no one leader—even if it’s a woman—can change the city alone. We must do it together.”

The former federal prosecutor and political outsider drew little notice last May when she announced her long-shot challenge to Mayor Rahm Emanuel for the Democratic mayoral nomination.

When Emanuel declined to seek a third term, several Democrats with far more name recognition than Lightfoot leaped into the political fray. But it was Lightfoot who claimed the most votes in the field of 14 in the February election, although she failed to gain the 50% threshold required to avoid a runoff.