Mass. Gen. Laws ch. 160 § 176A
Every railroad corporation shall equip each of its track motor cars operated between points in the commonwealth during the period from thirty minutes before sunset to thirty minutes after sunrise on the day next following with an electric headlight of sufficient candle power when lighted to render plainly visible during clear weather, at a distance of not less than three hundred feet in advance of such car, any track obstruction, warning sign or grade crossing, and with an electric tail light showing red to the rear when lighted, of sufficient candle power as to be plainly visible at a distance of three hundred feet, in clear weather, or with such a head or tail light or lights as any regulatory authority may require or prescribe for use in place thereof.
Mass. Gen. Laws ch. 160, § 176A