ceived meaning in other cases, be construed so, as to include the power to lay out and construct roads. The question is, whether that is the true sense of the words, as used in the constitution. And here, if ever, the rule of interpretation, which requires us to look at the nature of the instrument, and the objects of the power, as a national power, in order to expound its meaning, must come into operation.
§ 1145. But whatever be the extent of the power, narrow or large, there will still remain another inquiry, whether it is an exclusive power, or concurrent in the states. This is not, perhaps, a very important inquiry, because it is admitted on all sides, that it can be exercised only in subordination to the power of congress, if it be concurrent in the states. A learned commentator deems it concurrent, inasmuch as there seems nothing in the constitution, or in the nature of the thing itself, which may not be exercised by both governments at the same time, without prejudice or interference; but subordinate, because, whenever any power is expressly granted to congress, it is to be taken for granted, that it is not to be contravened by the authority of any particular state. A state might, therefore, establish a post-road, or post-office, on any route, where congress had not established any.[1] On the other hand, another learned commentator is of opinion, that the powder is exclusive in congress, so far as relates to the conveyance of letters, &c.[2] It is highly improbable, that any state will attempt any exercise of the power, considering the difficulty of carrying it into effect, without the co-operation of congress.
