Mitchell passed away Friday at age 57 after a battle with cancer. He served Rainbow PUSH for decades as Reverend Jesse Jackson Sr.'s right-hand man.
People across the city are remembering Mitchell. He died after a long fight with stage 4 myeloma.
The organization described him as someone who is inter-woven with Jackson's legacy, having worked beside him for nearly 30 years.
The Rainbow PUSH Coalition released a statement saying in part, "John was a General on the battlefield for Civil and Human Rights... John was the tantamount community leader and organizer. He was the best that mankind had to offer."
Mitchell leaves behind a wife and two children.