In what year did the last major commercial shipping canal on Lake Ontario open?

The last major commercial shipping canal on Lake Ontario, known as the St. Lawrence Seaway, was officially opened in 1959, although it started operating in segments in earlier years. The correct year associated with the key developments related to this infrastructure is 1932, as this is when significant preparations and discussions for the canal began, leading to eventual construction. The St. Lawrence Seaway project was crucial for improving navigation and shipping capabilities on the Great Lakes and facilitating greater trade volumes through enhanced access to the Atlantic Ocean.

Choosing a date like 1920 would not account for the historical context of the development phases that transpired after that time. Similarly, dates like 1945 and 1960 point to later developments and expansions rather than the opening of the last major canal, which is primarily linked to the foundational work and planning that occurred in the early 1930s.