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 settlement of the interior of the country led Congress to seek to facilitate access by first encouraging the construction of highways. In successive acts, it authorized construction of the Cumberland and the National Road from the Potomac across the Alleghenies to the Ohio, reserving certain public lands and revenues from land sales for construction of public roads to new states granted statehood. 1 Acquisition and settlement of California stimulated interest in railway lines to the west, but it was not until the Civil War that Congress voted aid in the construction of a line from the Missouri River to the Pacific; four years later, it chartered the Union Pacific Company. 2
The litigation growing out of these and subsequent activities settled several propositions. First, Congress may provide highways and railways for interstate transportation; 3 second, it may charter private corporations for that purpose; third, it may vest such corporations with the power of eminent domain in the states; and fourth, it may exempt their franchises from state taxation. 4