Ships are blocked in the St. Lawrence Seaway.

The obstruction, which was caused by the collapse of a concrete canal wall about 125 feet long, is expected to take weeks to clear, officials said. Fifty-five ships carrying grain, steel and military equipment are backed up at ports around the Great Lakes. Seaway pilots say critical facilities in the system have been deteriorating for years due to lack of maintenance. Last year, 126 ships were blocked when a lift bridge broke.