The twenty years from 1830 to 1850 saw great changes in the composition of the population of the Middle West. The opening of the Erie Canal in 1825 was an epoch-making event. It furnished a new outlet and inlet for northwestern traffic; Buffalo began to grow, and New York City changed from a local market to a great commercial center. But even more important was the place which the canal occupied as the highway for a new migration. In the march of the New England people from the coast, three movements are of especial importance: the advance from the seaboard up the Connecticut and Housatonic Valleys through Massachusetts and into Vermont; the advance thence to central and western New York; and the advance to the interior of the Old Northwest. The second of these stages occupied the generation from about 1790 to 1820; after that the second generation was ready to seek new lands; and these the Erie Canal and lake navigation opened to them, and to the Vermonters and other adventurous spirits of New England. It was this combined New York-New England stream that in the thirties poured in large volume into the zone north of the settlements which have been described. The newcomers filled in the southern counties of Michigan and Wisconsin, the northern countries of Illinois, and parts of the northern and central areas of Indiana. Pennsylvania and Ohio sent a similar type of people to the area adjacent to those States. In Iowa a stream combined of the Southern element and of these settlers sought the wooded tributaries of the Mississippi in the southeastern part of the State. In default of legal authority, in this early period, they formed squatter governments and land associations, comparable to the action of the Massachusetts men who in the first quarter of the seventeenth century "squatted" in the Connecticut Valley. A great forward movement had occurred, which took possession of oak openings and prairies, gave birth to the cities of Chicago, Milwaukee, St. Paul, and Minneapolis, as well as to a multitude of lesser cities, and replaced the dominance of the Southern element by that of a modified Puritan stock. The railroad system of the early fifties bound the Mississippi to the North Atlantic seaboard; New Orleans gave way to New York as the outlet for the Middle West, and the day of river settlement was succeeded by the era of inter-river settlement and railway transportation. The change in the political and social ideals was at least equal to the change in economic connections, and together these forces made an intimate organic union between New England, New York, and the newly settled West. In estimating the New England influence in the Middle West, it must not be forgotten that the New York settlers were mainly New Englanders of a later generation.