On Montgomery buses, the first four rows were reserved for whites. The rear was for blacks, who made up more than 75 percent of the bus system's riders. Blacks could sit in the middle rows until those seats were needed by whites. Then the blacks had to move to seats in the rear, stand or, if there was no room, leave the bus. Even getting on the bus presented hurdles: If whites were already sitting in the front, blacks could board to pay the fare but then they had to disembark and re-enter through the rear door.