Mo. Rev. Stat. § 391.260
It shall be the duty of every corporation, or company that now or hereafter may own, control, operate or manage any electrical railway in any part of this state, to furnish a heater in the front vestibule of the car for the convenience, health and comfort of the conductor and motorman operating, controlling and in charge of any and all its cars. This section shall not extend to electrical railways operated in cities having one hundred and fifty thousand or more inhabitants.
(RSMo 1939 § 5304)
Prior revisions: 1929 § 4898; 1919 § 10109