Between 1875 and 1880 the pooling system rapidly spread all over the Union. Wherever competition promised to regulate rates by the application of the law of supply and demand, the pool was resorted to as the never-failing remedy to preserve dividends on watered stock. As long as lake and canal navigation controlled the carriage of heavy freights between Chicago and New York by means of rates so low that railroads found it, or at least thought it, impossible to compete with them in the transportation of agricultural products during the greater part of the year, railroad pools between Chicago and New York could not be successfully maintained. In 1873 the railroads transported only about 30 per cent. of this kind of freight from the West to Eastern ports. Owing, however, to the rapid decrease of the cost of transportation, railroad companies from this time on were enabled to encroach rapidly upon the business of water routes, so that in 1876 they carried over 52 per cent. of the entire volume of agricultural products that were moved from the West to the East. As long as these products were carried almost entirely by water from lake ports to the East, New York, as the terminus of this route, enjoyed decided advantages over the other Atlantic ports. When, however, the railroads commenced to successfully compete with the water routes in the transportation of these commodities, a considerable share of this business was diverted to Boston, Philadelphia and Baltimore, and it soon became apparent that these ports, in some respects, enjoyed advantages for the export trade not possessed by New York. It was, therefore, not surprising that the business men of these cities, together with the railroads terminating in them, made every effort to come in for their share of the traffic which was drifting away from New York. Competition between the New York Central and the Pennsylvania Railroad for the Western through traffic dated back as far as 1869, the year in which both systems secured, through consolidation with connecting roads, through lines to Chicago. Rates fell in one year from $1.80 to 25 cents per hundred pounds. After a time the managers of the two companies met, and schedule rates were restored. Rates were, at least outwardly, maintained until the Baltimore and Ohio and the Erie system entered Chicago, and the Grand Trunk made connections with Milwaukee and other lake points, and thus disturbed through rates. All efforts to maintain the level of the old tariffs, through agreements, proved now fruitless, for both the Baltimore and Ohio and the Grand Trunk found it to their interest to pursue independent policies, and refused to have their hands tied by an agreement with roads that were interested in continuing, if possible, the commercial supremacy of New York.