On April 25, 1959, the St. Lawrence Seaway first opened. This 400 mile water rout connected Michigan with the Atlantic ocean.
On the plus side, this made shipping Michigan manufacturing goods abroad much easier. For example, the Detroit Marine Terminals reported an estimated 65% increase in foreign business during the first full month that the St. Lawrence Seaway was open, compared with the previous May. The Free Press called it the “answer to a centuries-old dream for a sea route into the heartland of America.”
On the negative side, it also allowed the introduction of foreign species such as Zebra Mussels into the Great Lakes.
Sources :
Michigan Historical Calendar, courtesy of the Clarke Historical Library at Central Michigan University.
Zlati Meyer, “Seaway opens, boosts business along lakes”, Detroit Free Press, April 22, 2012.
Pandora’s locks : the opening of the Great Lakes-St. Lawrence Seaway / Jeff Alexander. East Lansing, Mich. : Michigan State University Press, c2009.