As the population, territory, and wealth of the country increased and settlements extended into remote regions, the necessity for additional means of communication impressed itself upon all minds with a force which had not been experienced at the date of the formation of the Constitution, and more and more embarrassed those who were most anxious to abstain scrupulously from any exercise of doubtful power. Hence the recognition in the messages of Presidents Jefferson, Madison, and Monroe of the eminent desirableness of such works, with admission that some of them could lawfully and should be conducted by the General Government, but with obvious uncertainty of opinion as to the line between such as are constitutional and such as are not, such as ought to receive appropriations from Congress and such as ought to be consigned to private enterprise or the legislation of the several States. This uncertainty has not been removed by the practical working of our institutions in later times; for although the acquisition of additional territory and the application of steam to the propulsion of vessels have greatly magnified the importance of internal commerce, this fact has at the same time complicated the question of the power of the General Government over the present subject. In fine, a careful review of the opinions of all my predecessors and of the legislative history of the country does not indicate any fixed rule by which to decide what, of the infinite variety of possible river and harbor improvements, are within the scope of the power delegated by the Constitution; and the question still remains unsettled. President Jackson conceded the constitutionality, under suitable circumstances, of the improvement of rivers and harbors through the agency of Congress, and President Polk admitted the propriety of the establishment and support by appropriations from the Treasury of light-houses, beacons, buoys, and other improvements within the bays, inlets, and harbors of the ocean and lake coasts immediately connected with foreign commerce. But if the distinction thus made rests upon the differences between foreign and domestic commerce it can not be restricted thereby to the bays, inlets, and harbors of the oceans and lakes, because foreign commerce has already penetrated thousands of miles into the interior of the continent by means of our great rivers, and will continue so to extend itself with the progress of settlement until it reaches the limit of navigability.