highway use fee

consistently with the commerce clause, a State may impose upon vehicles used exclusively for interstate transportation a fair and reasonable tax as compensation for the privilege of using its highways for that purpose. ... where a state at its own expense furnishes special facilities for the use of those engaged in commerce, interstate as well as domestic, it may exact compensation therefor. The amount of the charges and the method of collection are primarily for determination by the state itself; and so long as they are reasonable and are fixed according to some uniform, fair, and practical standard, they constitute no burden on interstate commerce.