The makers of the Constitution never intended that the people of one state should regulate, or pay for supervising, the conduct of citizens of another state. They made a division of governmental powers between nation and states along broad and obvious lines. To the Federal Government were entrusted matters of a strictly national character--foreign relations, interstate commerce, fiscal and monetary system, post office, patents and copyrights. Everything else was reserved, to the states or the people. Here was a scheme at once explicit and elastic. Explicit as to the nature of the functions to be performed by the National Government; elastic enough to permit the exercise of all other powers reasonably incidental to the powers expressly granted. The Constitution is not, and never was intended to be, a strait-jacket. Proofs abound of the adequacy of the constitutional scheme to deal with changing conditions. For example, when the Constitution was adopted, railroads, the most powerful economic force in our present civilization, were unknown. Nevertheless, the Constitution contains adequate provision for dealing with the railroads. They are instruments of interstate commerce and may be controlled by the Federal Government under the express grant of power to regulate such commerce. Similar considerations apply in the case of those nationwide industrial combinations popularly known as "trusts." Their activities are largely in the field of interstate commerce and are subject to control as such by the Federal Government. Theoretically, only such activities of the railroads and trusts as are of an interstate character fall within the federal jurisdiction. Everything else lies within the jurisdiction of the states. However, a practical people will not long permit matters which are essentially single and entire in their nature (for example, railroad classifications and rates) to be split up merely for purposes of legal jurisdiction and control. In such matters, therefore, some measure of federal encroachment is inevitable in order that industry and progress shall not be hampered. The encroachment, however, is more apparent than real. The industries are national in scope, and all the activities of each are more or less interwoven and interdependent. Hence state regulation of the intrastate activities may sometimes be overruled as an interference with federal regulation of the interstate commerce. There is nothing in this which involves any real violation of the Constitution. It is merely an application of Marshall's doctrine of implied powers.