S.C. Code Ann. § 59-67-80: Windshield wiper, brakes, lights, and rear view mirrors.

Every school bus shall be equipped with a power-driven windshield wiper, adequate brakes and efficient lights which shall at all times when in use be in good working order and also with a rear view mirror or mirrors of such dimensions as will enable the driver, from the driver's seat, to see reflected in them not only the occupants of the vehicle but also the road to the left and to the rear of the vehicle for a proper distance adequately to observe traffic in his rear.