Welland Canal
The St. Lawrence Seaway was preceded by several other canals. In 1871, locks on the St. Lawrence allowed transit of vessels long, wide, and deep. The First Welland Canal, constructed between 1824 and 1829, had a minimum lock size of long, wide, and deep, but it was generally too small to allow passage of larger oceangoing ships. The Welland Canal's minimum lock size was increased to long, wide, and deep for the Second Welland Canal; to long, wide, and deep with the Third Welland Canal; and to long, wide, and deep for the current (Fourth) Welland Canal.