Cotton cultivation became more than ever the dominant industry of the entire South; most of the manufacturing was done in the New England and Middle Atlantic States; the Northern Central States were devoted primarily to the production of grain and live stock. The development of the country was accompanied by the construction of transportation facilities to care for the expanding trade. A large number of important canals were completed; the Ohio River was joined to Lake Erie; Pittsburgh and Philadelphia were connected by a rail and water line; the Illinois River was connected with Lake Michigan at Chicago; the St. Mary's Falls Canal was built to aid the navigation of the Great Lakes, and many other waterways of lesser importance were constructed. Railroads grew rapidly in favor and as time went on they were built in increasing numbers and the construction of canals was practically abandoned. Before 1840 over 2,800 miles of track were laid and by 1850 the mileage amounted to 9,000. The decade from 1850 to 1860 was a period of extensive railway construction, especially in the Northern Central States, where more than 10,000 miles were built. Early in the decade the trunk lines of the Eastern States were pushed across the mountains and through railway connection was established between the Mississippi Valley and the Atlantic Ocean. New York was connected with Chicago by a direct rail route in 1853, and with St. Louis in 1855, and in 1858 a railroad reached the Missouri River. In the South, roads were built into the interior from all the important cities on the Atlantic and Gulf coasts. In 1860 there was a total of 30,626 miles of railroad in the entire country. With the growth of population and wealth, the diversification of industry and the development of canals and railroads, there was a great increase in internal commerce. The trade of this period consisted of a few well-defined currents flowing between certain sections. A large volume of products, mainly agricultural, went from the Central States to the East, and a traffic of less volume but of greater value moved in the reverse direction. There was a heavy internal movement from the Northern to the Southern States and a light movement from the South to the North. Aside from these movements, there was an over-land trade by pack-horse and wagon with the Far West which became of particular importance after the discovery of gold. For the sake of greater clearness, these different currents of trade will be considered separately in the order named. 1. TRADE BETWEEN THE EASTERN AND CENTRAL STATES