The power is there restrained to Indians not members of any of the states, and is not to violate or infringe the legislative right of any state within its own limits. What description of Indians were to be deemed members of a state, had been a question of frequent contention and perplexity in the federal councils. And how the trade with Indians, though not members of a state, yet residing within its legislative jurisdiction, could be regulated by an external authority, without so far intruding on the internal rights of legislation, seems altogether incomprehensible.
A regular system of free and speedy communication, is of vital importance to the mercantile interest, but on a wider scale we must also admit it to be of the first consequence to the general benefit. In time of peace, it tends to keep the people duly informed of their political interests; it assists the measures of government, and the private intercourse of individuals. During a war, the rapid communication of intelligence, by means of the post, and the greater facility of transferring bodies of men or munitions of war, to different places, by the aid of good roads, are evident advantages. If these establishments should in practice produce no revenue, the expense would be properly chargeable to the Union, and the proceeds of taxation in the common forms be justly applied to defray it. If, however, as has proved to be the case, the post office yields a revenue, which is with the other revenues of the United States applicable only to the general service, it is obvious, that no state ought to interfere by establishing a post office of its own. This is therefore an exclusive power so far as relates to the conveyance of letters, &c. In regard to post roads, it is unnecessary, and therefore would be unwarrantable in congress where a sufficient road already exists, to make another; and on the other hand, no state has a power to deny or obstruct the passage of the mail, or the passage of troops, or the property of the United States over its public roads.
The power given to congress, in respect to this subject, was brought into operation soon after the Constitution was adopted, and various provisions have at different times been enacted, founded on the principle of its being an exclusive power.
It has been made a constitutional question, whether congress has a right to open a new mail road through a state or states for general purposes, involving the public benefit, and the same doubt has been extended to the right of appropriating money in aid of canals through states.
At the end of the Revolution, the United States was in a difficult economic position. Its resources were drained, its credit shaky and