Mo. Rev. Stat. § 151.320
On or before the fifteenth day of April in each year, the president or other authorized officer of every street railroad company in every city of this state whose line is now or shall hereafter become so far completed and in operation as to run electric cars, trolley cars, motorbuses, or cars propelled by any other device for the transportation of passengers, shall furnish to the state tax commission a statement duly subscribed and sworn to by the president or other authorized officer, before some officer authorized to administer oaths, setting out in detail the distributable property of the street railroad, the true value in money thereof and such information concerning itself and all of its property, wherever situated, as the state tax commission may reasonably require for the purpose of estimating the true value in money of such distributable property of the street railroad company in this state and for apportioning the valuation for assessment of such property among the various counties.
§ 151.320, RSMo
Effective 6/20/1986