 The Blue Water Bridge links Sarnia and its neighbouring village of Point Edward to the city of Port Huron in the United States . It spans the St. Clair River , which connects Lake Huron to Lake St. Clair . The bridge 's original three @-@ lane span , opened in 1938 , was twinned on 22 July 1997 , making the bridge the fourth busiest border crossing in Ontario . The Blue Water Bridge border crossing makes use of both the <unk> ( frequent traveler program ) and the Free and <unk> Trade ( <unk> ) program . <unk> Highway 402 with the American Interstate 94 ( I @-@ 94 ) and I @-@ 69 , the bridge forms part of the <unk> <unk> , and is one of the most important <unk> on the north – south truck routes . 
