[70 copo]

Some History is in order:

FEDERAL MOTOR
VEHICLE SAFETY
STANDARDS
(Title 49 Code of Federal
Regulations Part 571)

Standard No. 111 - Rearview Mirrors - Passenger Cars, Multipurpose Passenger Vehicles, Trucks, Buses, School Buses and Motorcycles
(Effective 1-1-68)
This standard specifies requirements for the performance and location of inside and outside rearview mirrors. Its purpose is to reduce the number of deaths and injuries that occur when the driver of a motor vehicle does not have a clear and reasonably unobstructed view to the rear.

The enactment of this standard quickly caused individual states to develop rule making at the state level. This was specific for the usage and design of the vehicle. For example even before the enactment of FMVSS 111:

<span style="font-weight: bold">Alabama</span>
Alabama Vehicle Code, Section 32-5-214
Mirrors.
Every motor vehicle, operated singly or when towing any other vehicle, shall be equipped with a mirror so located as to reflect to the driver a view of the highway for a distance of at least 200 feet to the rear of such motor vehicle. (Acts 1927, No. 347, p. 348; Code 1940, T. 36, §37; Acts 1959, No. 292, p. 860.)

In Alabama towing a simple trailer or having materials stacked up too high in your rear passenger seat could cross up with the law as early as 1959, and land you a citation.