In the 18th century New York was smaller than Philadelphia and Boston. Today it is the largest city in America. How can the change in its size and importance be explained？
To answer this question we must consider certain facts about geography， history，and economics. Together these three will explain the huge growth of America’s most famous city.
The map of the Northeast shows that four of the most heavily populated areas in this region are around seaports. At these points materials from across the sea enter the United States， and the product of the land are sent there for export across the sea.
Economists know that places where transportation lines meet are good places for making raw materials into finished goods. That is why seaports often have cities nearby. But cities like New York needed more than their geographical location in order to become great industrial centers. Their development did not happen simply by chance.
About 1815，when many Americans from the east coast had already moved toward the west，trade routes from the ports to the central regions of the country began to be a serious problem. The slow wagons of that time，drawn by horses or oxen，were too expensive for moving heavy freight very far. Americans had long admired Europe’s canals. In New York State a canal seemed the best solution to the transportation problem. From the eastern end of Lake Erie all the way across the state to the Hudson River there is a long strip of low land. Here the Erie Canal was constructed. After several years of work it was completed in 1825.
The canal produced an immediate effect. Freight costs were cut to about one-tenth of what had been. New York City，which had been smaller than Philadelphia and Boston， quickly became the leading city of the coast. In the years that followed， transportation routes on the Great Lakes were joined to routes on the Mississippi River. Then New York City became the end point of a great inland shipping system that extended from the Atlantic Ocean far up the western branches of the Mississippi.
