Nov 24, 2005 — In the 1950's, engineers carved a shipping channel from the Atlantic Ocean to the Great Lakes via the St. Lawrence River. The St. Lawrence Seaway was supposed to make ports like Duluth and Chicago main players in global commerce. Today, the Seaway operates at less than half its capacity. That's because only five percent of the world's cargo fleet can fit through its locks and channels. For decades, the shipping industry has pushed for expansion. Those plans are now on hold. David Sommerstein has this next story in our series on threats to the Great Lakes.