|An old aerial photo of ore carrier ships heading for Lake Huron: the USA to the left, Canada to the right.|
The Blue Water Bridge linking Port Huron, Michigan, USA and Sarnia, Ontario, Canada, is actually now two bridges: the first was opened on 10 October 1938, at which time it consisted of two vehicle lanes and sidewalks. The sidewalks were removed in the 1980s to provide an extra traffic lane.
Like Auckland's bridge, no provision was made for railway lines, however, this wasn't a result of Steven Joyce type thinking, as there was already a railway tunnel under the St. Clair River.
The original span is a cantilever truss bridge with a total length of 6,178 feet (1,883 metres) and a main span of 871 feet (265 metres).
Like Auckland's bridge, more capacity was needed, and a second span was opened on 22 July 1997. This is a continuous tied-arch bridge with a total length of 6,109 feet (1,862 metres) and a main span of 922 feet (281 metres).
Westbound vehicles (to the USA) use the three lanes on the older bridge, eastbound vehicles (to Canada) use the three lanes on the newer bridge. Together, the bridges are the second-busiest crossing between the US and Canada, after the Ambassador Bridge at Detroit-Windsor. The Blue Water Bridges are jointly owned and maintained by Canada and the United States: Blue Water Bridge Canada is in charge of the Canadian side, and the Michigan Department of Transportation (MDOT) is in charge of the U.S. side. A toll is charged to cross the bridges to pay for maintenance.