The Erie canal lowered the cost of shipping by 95%. Also, the cost of food in the East lowered too. Before the Canal was built Philadelphia was a major port on the journey to the west, but now since New York City was located right on the Hudson, it became became a center of trade and exceeded Philadelphia. In addition to New York City, Buffalo and New York State gained a lot of money, people and business.
Because Irish immigrants took a huge part in the construction, new Irish communities formed along the canal. Also, Many people got jobs driving boats up and down the Canal. In addition, trade with other countries improved. For example, England and Canada started to buy wheat from the mid-west region.
Being able to access The Great Lakes easier allowed more people to more westward more easily and cheaply.