Meaning of Among the Several States in the Commerce Clause

Article I, Section 8, Clause 3:
[The Congress shall have Power . . . ] To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes; . . .
The Supreme Court has interpreted the phrase among the several states to exclude transactions that occur wholly within a state. In Gibbons v. Ogden, Chief Justice John Marshall observed that the phrase among the several States was not one which would probably have been selected to indicate the completely interior traffic of a state.1 He noted that although the phrase may very properly be restricted to that commerce which concerns more states than one,2[c]ommerce among the states, cannot stop at the external boundary line of each state, but may be introduced into the interior.3 Identifying transactions covered by the Commerce Clause, he stated:
The genius and character of the whole government seem to be, that its action is to be applied to all the external concerns of the nation, and to those internal concerns which affect the states generally; but not to those which are completely within a particular state, which do not affect other states, and with which it is not necessary to interfere, for the purpose of executing some of the general powers of the government.4
Subsequent to Gibbons, the Court held in a number of cases that Congress’s Commerce Clause power did not extend to commerce that was exclusively internal to a state.5 In these nineteenth and early twentieth century cases, the Court seemingly tied Congress’s interstate commerce power to cross-border transactions notwithstanding Marshall’s Gibbons reasoning that Congress’s Commerce Clause power could extend to intrastate commerce that affects other states or implicates congressional power.6 In its 1905 Swift & Co. v. United States decision, the Court revisited Marshall’s expansive reading of the Commerce Clause to reason that, in a current of commerce, each element was within Congress’s Commerce Clause power.7 Looking at the interrelationship of industrial production to interstate commerce,8 the Court noted that the cumulative impact9 of minor transactions can impact interstate commerce.10