The Blue Water Bridge link Sarnia and its neighbouring village of Point Edward to the city of Port Huron in the United States . It span the St. Clair River , which connect 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 make use of both the NEXUS ( frequent traveler program ) and the Free and Secure Trade ( FAST ) program . Linking Highway 402 with the American Interstate 94 ( I @-@ 94 ) and I @-@ 69 , the bridge form part of the NAFTA Superhighway , and is one of the most important gateways on the north – south truck routes .