Article 1, Section 8, Clause 7
William Rawle, A View of the Constitution of the United States 103--4 1829 (2d ed.)
The power to establish post offices and post roads, has a necessary connexion with the promotion of commerce and the general welfare of the Union.
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. If we adhere to the words of the text, we are confined to post roads; but it appears to the author to be one of those implied powers which may fairly be considered as within the principles of the Constitution, and which there is no danger in allowing. The general welfare may imperiously require communications of either of these descriptions. A state is bound to consult only its own immediate interests, and not to incur expense for the benefit of other states. The United States are bound to uphold the general interest at the general expense. To restrain them to pointing out the utility of the measure, and calling on particular states to execute it, would be partially to recall the inefficiency of the old government and to violate the main principle of the present one. If any political evil could result from the procedure, it would present a strong argument against the allowance of the power; but good roads, and facile, aquatic communications, while they promote the prosperity of the country, cannot be seriously alleged to affect the sovereignty of the states, or the liberties of the people. It is doubtful whether tolls for passage on it, can be constitutionally exacted.
Rawle, William. A View of the Constitution of the United States of America. 2d ed. Philadelphia, 1829. Reprint. New York: Da Capo Press, 1970.
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