Jim Crow laws were several laws governing black behavior regarding whites - always in favor of whites. In public transport any person of color had to give up their seat and sit at the back even if the black was an elderly or pregnant woman and the white a physically fit male. Rosa refused to sit at the back of the bus and refused to give her seat up to a white man. When she was kicked off the bus and arrested every black in the city boycotted public transport and brought the city to its knees because blacks were the largest users of public buses. Do a net search on 'Jim Crow' and 'Rosa Parks'. Youll get all sorts of good info.