I would check your state's vehicle code for the answer. As an example here are two section of the California Vehicle Code that pretty much give the answer, at least for California.
Backup Lamps
24606. (a) Every motor vehicle, other than a motorcycle, of a type subject to registration and manufactured on and after January 1, 1969, shall be equipped with one or more backup lamps either separately or in combination with another lamp. Any vehicle may be equipped with backup lamps.
(b) Backup lamps shall be so directed as to project a white light illuminating the highway to the rear of the vehicle for a distance not to exceed 75 feet. A backup lamp may project incidental red, amber, or white light through reflectors or lenses that are adjacent or close to, or a part of, the lamp assembly.
(c) Backup lamps shall not be lighted except when the vehicle is about to be or is backing or except in conjunction with a lighting system which activates the lights for a temporary period after the ignition system is turned off.
(d) Any motor vehicle may be equipped with a lamp emitting white light on each side near or on the rear of the vehicle which is designed to provide supplemental illumination in an area to the side and rear not lighted by the backup lamps. These lamps shall be lighted only with the backup lamps.
Rear-facing Auxiliary Lamps
24616. (a) A motor vehicle may be equipped with one or two rear-facing auxiliary lamps. For the purposes of this section, a rear-facing auxiliary lamp is a lamp that is mounted on the vehicle facing rearward. That lamp shall meet the photometric and performance requirements of the Society of Automotive Engineers Standard J1424 for cargo lamps.
(b) A rear-facing auxiliary lamp may project only a white light, with the main cone of light projecting both rearward and downward. The main cone of light shall illuminate the road surface or ground immediately rearward of a line parallel to the rear of the vehicle for a distance not greater than 50 feet. The main cone of light may not project to the front or sides of the vehicle.
(c) A rear-facing auxiliary lamp may be activated only when the vehicle is stopped. A vehicle equipped with a rear-facing auxiliary lamp shall also be equipped with a system that allows activation of the lamp only when the vehicle is in the "park" setting, if the vehicle is equipped with an automatic transmission, or in the "neutral" setting with the parking brake engaged, if the vehicle is equipped with a manual transmission.
(d) A vehicle equipped with a rear-facing auxiliary lamp may have an activation switch accessible to the operator from the rear of the vehicle.
Seeing as to how OP is in Minnesota I also did a quick scan of their code and found that it is not quite as detailed. About the closest thing I could find is this.
169.55 LIGHTS ON ALL VEHICLES.
Subdivision 1.Lights or reflectors required.
At the times when lighted lamps on vehicles are required each vehicle including an animal-drawn vehicle and any vehicle specifically excepted in sections 169.47 to 169.79, with respect to equipment and not hereinbefore specifically required to be equipped with lamps, shall be equipped with one or more lighted lamps or lanterns projecting a white light visible from a distance of 500 feet to the front of the vehicle and with a lamp or lantern exhibiting a red light visible from a distance of 500 feet to the rear, except that reflectors meeting the maximum requirements of this chapter may be used in lieu of the lights required in this subdivision. It shall be unlawful except as otherwise provided in this subdivision, to project a white light to the rear of any such vehicle while traveling on any street or highway, unless such vehicle is moving in reverse. A lighting device mounted on top of a vehicle engaged in deliveries to residences may project a white light to the rear if the sign projects one or more additional colors to the rear. An authorized emergency vehicle may display an oscillating, alternating, or rotating white light used in connection with an oscillating, alternating, or rotating red light when responding to emergency calls.
169.64 PROHIBITED LIGHTS; EXCEPTIONS.
Subdivision 1.Bright light.
Any lighted lamp or illuminating device upon a motor vehicle, other than a headlamp, a spot lamp, or an auxiliary driving lamp, which projects a beam of light of an intensity greater than 300-candle power, shall be so directed that no part of the beam will strike the level of the roadway on which the vehicle stands at a distance of more than 75 feet from the vehicle.