Tex. Rev. Civ. Stat. art. 3861
The Railroad Commission of Texas shall have power, and it shall be its duty, to fix and establish reasonable and just rates of charges for each class or kind of property, money, papers, packages and other things, to be received and charged for by each express company, and, which, by the contract of carriage, are to be transported by such express company between points wholly within this State. Such rates shall be made to apply to all such companies, and may be changed or modified by said Commission from time to time in such, manner as may become necessary. Said Commission shall have the same power to make and prescribe such rules and regulations for the government and control of such express companies as is, or may be, conferred upon said Commission for the regulation of railroads.
Tex. Rev. Civ. Stat. Ann. art. 3861