CHICAGO, United States - The US city of Chicago has made history by electing an African-American woman as its mayor for the first time.

Lori Lightfoot is a former federal prosecutor who has not held political office before.

She fought off competition from 13 other candidates and dominated the final run-off election with more than 74% when the vote was called.

Ms Lightfoot is also the city's first gay mayor and celebrated on-stage with her wife and daughter.

"Out there tonight a lot of little girls and boys are watching. They're watching us. And they're seeing the beginning of something, well, a little bit different," she told a crowd celebrating her victory on Wednesday night.

The 56-year-old was viewed as an outsider to the race, and campaigned on a platform to end political corruption and help lower-income families.

Gun crime and policing were also high on the agenda in a city plagued by high levels of gang violence and murder.(FA)