County Commissioner Brandon Johnson speaks at a mayoral runoff rally March 30, 2023. [Don Vincent/The Daily Line]

Cook County Comm. Brandon Johnson (D-1) will vacate his seat on the county board of commissioners when he becomes Chicago’s next mayor in May.  

The process for selecting a replacement to serve on the board will come down to a panel of local Democratic Party officials but also tees up a special election for the soon-to-be-open seat in 2024.