D.C. Mun. Regs. tit. 18 § 710
All vehicles, including animal-drawn vehicles and including those referred to in § 700.5 not specifically required to be equipped with lamps, shall at the times specified in § 703 be equipped with at least one (1) lighted lamp or lantern exhibiting a white light visible from a distance of five hundred feet (500 ft.) to the front of the vehicle and with a lamp or lantern exhibiting a red light visible from a distance of five hundred feet (500 ft.) to the rear.
Each self-propelled unit of farm equipment not equipped with an electric lighting system shall, pursuant to §§ 703 and 710.1, be equipped with two (2) red reflectors visible from a distance of at least six hundred feet (600 ft.) to the rear when directly in front of the beams of head lamps being operated in accordance with the law.
D.C. Mun. Regs. Tit. 18, § 710