During the 1840s and then continuing after the American Civil War, shipping in New York City – which then consisted only of Manhattan – shifted in large part from the East River and the area around South Street to the Hudson River, where the longer piers could more easily handle the larger ships which were then coming into use. In addition, the dredging of the sand bars which lay across the entrance to New York Harbor from the Atlantic Ocean made it easier for ships to navigate to the piers on the Hudson, rather than use the "back door" via the East River to the piers there. Later, the Hudson River piers also received freight via railroad cars ferried across the river from New Jersey.