23 V.S.A. § 1305: Mirror required

All motor trucks and motor vehicles towing a trailer or semi-trailer shall be equipped with a mirror not less than five inches in diameter or with less than 25 square inches of reflective area so attached that the driver shall at all times have a reflected view of other vehicles approaching from the rear. The mirror shall be attached in a manner that complies with the width requirements of section 1431 of this title. The extended rear-view mirror shall be retracted or removed when not towing a trailer or semi-trailer.