430 U.S. 274 (1977)
Complete Auto Transit, Inc., a Michigan corporation, transports motor vehicles by motor carrier for General Motors Corporation.1 General Motors assembles vehicles outside Mississippi for dealers within the State.2 The vehicles arrive by rail in Jackson, Mississippi, and within about 48 hours appellant loads them onto its trucks for delivery to the dealers.3 Appellant receives payment on a contract basis for this intrastate leg of the transportation.4
The Mississippi State Tax Commission assessed privilege taxes against appellant for the periods from August 1, 1968, through July 31, 1972.5 The assessments, made under Mississippi Code provisions levying five percent of gross income on transportation businesses operating between points within the State, totaled $122,160.59 for the first three years and $42,990.89 for the final year.6 Appellant paid the assessments under protest after receiving letters from the Commission in October 1971 and December 1972.7
In April 1973 appellant filed a refund action in the Chancery Court of the First Judicial District of Hinds County.8 The Chancery Court sustained the assessments in an unreported opinion.9 On appeal the Mississippi Supreme Court affirmed the judgment in a unanimous decision.10
Appellant did not claim in its complaint that its activities lacked a sufficient nexus with Mississippi, that the tax discriminated against interstate commerce, that the tax was unfairly apportioned, or that the tax bore no relation to services provided by the State.11 The Mississippi Supreme Court observed that appellant maintained a large operation in the State and benefited from state services such as police protection.12
Whether Mississippi runs afoul of the Commerce Clause when it applies the tax it imposes on the privilege of doing business within the State to appellant’s activity in interstate commerce?13
A state tax on interstate commerce does not violate the Commerce Clause if it is applied to an activity with a substantial nexus with the taxing State, is fairly apportioned, does not discriminate against interstate commerce, and is fairly related to the services provided by the State.14 The Court overrules the formalistic Spector rule.15 That rule prohibited taxes labeled as on the privilege of doing business when applied to interstate commerce.16 The rule bears no relationship to economic realities.17 The Commerce Clause is concerned with the practical effect of the tax.18
Yes. Mississippi's tax satisfies the four-part test under the Commerce Clause.19 The activity of transporting vehicles from the railhead in Jackson to dealers within the State has a substantial nexus with Mississippi, as appellant maintains a large operation there.20 The tax is fairly apportioned because there is no possibility of other states duplicating the tax.21 No claim was made that the tax discriminates against interstate commerce or that it is not fairly related to the services provided by the State, including police protection from which appellant benefits.22
Appellant made no claims to the contrary in the lower courts.23
Mississippi does not run afoul of the Commerce Clause when it applies its privilege tax to appellant's activity in interstate commerce.24