=Interstate Commerce.=—During the years which immediately followed the Revolutionary War the several states were free to make their own regulations for the encouragement and control of commerce. Accordingly they began to compete with one another for trade, each trying to increase its own prosperity at the expense of the others. This led to ill-feeling, of course, and finally to retaliation. One state would offer inducements to bring vessels into its ports; the others, in self-defence, held out even greater inducements. This rivalry soon got to the point where it looked as if some of the states might come to blows.[160] So, when the framers of the national constitution met at Philadelphia in 1787, they gave particular attention to the problem of ending this unwholesome rivalry by placing the regulation of all interstate and foreign commerce under a single, central authority. [Sidenote: The constitution places interstate commerce under federal control.] The national constitution, therefore, transferred this regulating power from the states to Congress, by vesting in it the power “to regulate commerce with foreign nations, and among the several states, and with the Indian tribes”. This is a very important provision in the supreme law of the land, and it has had a far-reaching influence in building up the commerce of the United States. One can realize what might have happened if every state had been left at liberty to put duties upon goods imported from other states and to bestow all sorts of advantages upon its own merchants. Under such an arrangement a closely-knit, unified country would have been impossible, for freedom of trade within a nation is an indispensable factor in bringing the whole people into close and friendly relations. The adoption of this clause in the national constitution meant that all trade, from one end of the land to the other, could be carried on freely, without let or hindrance, subject only to such uniform regulations as Congress might provide. [Sidenote: This control is now very extensive.] In the days when the national constitution was adopted, the carriers of commerce were few and primitive. Trade between different states was conducted by wagon and sailing vessels; there were no railroads, steamships, street cars, motor trucks, telegraphs, telephones, or parcels post. The cost of transporting goods was so great that it did not pay to ship them far. Goods were made almost wholly for the local market. But when the constitution endowed Congress with the power “to regulate commerce” it gave to this body a right which has been sufficiently broad to cover all the great developments of the past hundred years. Whatever comes within the term “commerce”, no matter howsoever carried on, is within the purview of Congress if it concerns more than a single state.