Cook County Commissioner Brandon Johnson became the 57th mayor of Chicago Tuesday night when he defeated fellow Democrat Paul Vallas in a run-off election. Johnson garnered 286,647 votes to 270,775 votes for Vallas. Succeeding Mayor Lori Lightfoot, the 47-year-old Johnson will lead the third-largest city in the U.S., which has seen a marked increase in violent crime over the last five years including murder and car thefts Cook County Commissioner Brandon Johnson became the 57th mayor of Chicago Tuesday night when he defeated fellow Democrat Paul Vallas in a run-off election. Johnson garnered 286,647 votes to 270,775 votes for Vallas. Succeeding Mayor Lori Lightfoot, the 47-year-old Johnson will lead the third-largest city in the U.S., which has seen a marked increase in violent crime