Syllabus
fuel.” 188 Wash. 2d 55, 69, 392 P. 3d 1014, 1020. It added that “travel on public highways is directly at issue because the tax [is] an importation tax.” Id., at 67, 392 P. 3d, at 1019. The incidence of a tax is a question of state law, Oklahoma Tax Comm’n v. Chickasaw Nation, 515 U. S. 450, 461, and this Court is bound by the Washington Supreme Court’s interpretation of Washington law, Johnson v. United States, 559 U. S. 133, 138. Nor is there any reason to doubt that the Washington Supreme Court meant what it said when it interpreted the statute. In the statute’s own words, Washington “impose[s] upon motor vehicle fuel licensees,” including “licensed importer[s],” a tax for “each gallon of motor vehicle fuel” that “enters into this state,” but only “if . . . entry is” by means of “a railcar, trailer, truck, or other equipment suitable for ground transportation.” Wash. Rev. Code §§82.36.010(4), 82.36.020(1), (2), 82.36.026(3). Thus, Cougar Den owed the tax because Cougar Den traveled with fuel by public highway. See App. 10a–26a; App. to Pet. for Cert. 55a. Pp. 4–10.
- (b) The State of Washington’s application of the tax to Cougar Den’s importation of fuel is pre-empted by the Yakama Nation’s reservation of “the right, in common with citizens of the United States, to travel upon all public highways.” This conclusion rests upon three considerations taken together. First, this Court has considered this treaty four times previously; each time it has considered language very similar to the language now before the Court; and each time it has stressed that the language of the treaty should be understood as bearing the meaning that the Yakamas understood it to have in 1855. See United States v. Winans, 198 U. S. 371, 380–381; Seufert Brothers Co. v. United States, 249 U. S. 194, 196–198; Tulee v. Washington, 315 U. S. 681, 683–685; Washington v. Washington State Commercial Passenger Fishing Vessel Assn., 443 U. S. 658, 677–678. Thus, although the words “in common with” on their face could be read to permit application to the Yakamas of general legislation (like the legislation at issue here) that applies to all citizens, this Court has refused to read “in common with” in this way because that is not what the Yakamas understood the words to mean in 1855. See Winans, 198 U. S., at 379, 381; Seufert Brothers, 249 U. S., at 198–199; Tulee, 315 U. S., at 684; Fishing Vessel, 443 U. S., at 679, 684–685. Second, the historical record adopted by the agency and the courts below indicates that the treaty negotiations and the United States’ representatives’ statements to the Yakamas would have led the Yakamas to understand that the treaty’s protection of the right to travel on the public highways included the right to travel with goods for purposes of trade. Third, to impose a tax upon traveling with certain goods burdens that travel. And the right to travel on the public highways without such burdens is just what the treaty protects. Therefore,
