If the military idea, the notion of its necessity as a feature of the national defense, was the determining factor in initiating the canal project, it remains a fact that its chief use will be commercial, and that its money return, whether small or large, nearly all will be derived from tolls assessed upon merchant vessels passing through it. [Illustration: THE THREE PRESIDENTS UNDER WHOSE DIRECTION THE CANAL WAS BUILT] [Illustration: VENDERS IN THE STREETS OF PANAMA] [Illustration: A NATIVE BOY MARKETING] The question of the probable traffic the canal will be called upon to handle was studied as perhaps no other world-wide problem of transportation ever was. Prof. Emory R. Johnson was the student of this phase of the question from the beginning to the end. He estimates that the canal in the first few years of its operation will have a traffic of 10,000,000 tons of shipping each year, and that by 1975 this will have increased to 80,000,000 tons, the full capacity of the canal in its present form. Provision has been made against this contingency by the engineers who have so constructed the canal that a third set of locks at each end may be constructed at a cost of about $25,000,000, and these will be sufficient almost to double the present ultimate capacity, and to take care of a larger volume of traffic than now can be foreseen. Americans are interested, first of all, in what the canal will do for their own domestic trade. It brings Seattle 7,800 miles nearer to New York; San Francisco, 8,800 miles nearer to New Orleans; Honolulu 6,600 miles nearer to New York than by the Strait of Magellan. Such saving in distance for water-borne freight works a great economy, and inevitably must have a tremendous effect upon transcontinental American commerce. In foreign commerce, also, some of the distances saved are tremendous. For instance, Guayaquil, in Ecuador, is 7,400 miles nearer to New York by the canal than by the Strait of Magellan; Yokohama is nearly 4,000 miles nearer to New York by Panama than by Suez; and Melbourne is 1,300 miles closer to Liverpool by Panama than by either Suez or the Cape of Good Hope. Curiously enough, the distance from Manila to New York, by way of Suez and Panama, is almost the same, the difference in favor of Panama being only 41 miles out of a total of 11,548 miles. The difference in distance from Hongkong to New York by the two canals is even less, being only 18 miles, this slight advantage favoring Suez. But it is not by measure of distances that the effect of the canal on international commerce may be measured. It spells the development of the all but untouched western coast of South America and Mexico. It means a tremendous up-building of foreign commerce in our own Mississippi Valley and Gulf States. It means an unprecedented commercial and industrial awakening in the States of our Pacific coast and the Provinces of Western Canada.