The seaway's opening is often credited with making the Erie Canal obsolete and causing the severe economic decline of several cities along the canal in Upstate New York. But by the turn of the 20th century, the Erie Canal had already been largely supplanted by the railroads, which had been constructed across New York and could carry freight more quickly and cheaply. Upstate New York's economic decline was precipitated by numerous factors, only some of which had to do with the Saint Lawrence Seaway.