the legislature to impose the tax or by the courts in reference to it, the law cannot be sustained if it operates to burden or regulate interstate business. Galveston, H. & S. A. R. Co. v. Texas, 210 U. S. 217, 227. Quaker City Cab Co. v. Pennsylvania, 277 U. S. 389, 401. Macallen Co. v. Massachusetts, 279 U. S. 620, 625.
The franchise tax upon gross earnings does not purport to be and is not claimed as ,a charge or rental for the use of property belonging to the State or any of its subdivisions. Indeed the appellee insists, and rightly so, that the right to construct, maintain and use mains and lines in streets is property owned by appellant; and it argues that the percentage of gross earnings exacted is a tax on that property right. Clearly the State, when passing the Act making the assessment, acted, not as a proprietor demanding compensation for the use of its property, but as sovereign imposing a tax for the support of government. Cf. St. Louis v. Western Union Telegraph Co., 148 U. S. 92, 97.
In the title and throughout the Act the distinction is made between the tax on property and the franchise tax on gross receipts. The levying provision (§5) defines the exaction as a “ franchise tax upon the annual gross receipts ” and elsewhere in the Act it is referred to briefly as “ franchise tax.” All real and personal property is required to be taxed by districts at local rates according to value; the franchise tax is a percentage of gross receipts; and it is declared to be in lieu, not of any property tax, but of all other franchise taxes.
. And, as under the state constitution property is required to be assessed by finiform rules according to its true value, the legislature may not reasonably be deemed to have intended direct valuation and assessment of some of the property at local rates and the measurement of the value of other elements of the plant by percentage- of gross earnings increasing on a sliding scale from 2 per cent, in 1917 to 5 per cent, in 1920 and thereafter. North