This image shows the road deck and truss design of the Blue Water Bridge, which links the cities of Port Huron, Michigan and Point Edward, Ontario.
There is no description on the back of this card. The legend on the front states:
Blue Water Bridge over St. Clair River at Point Edward, near Sarnia, Ontario, Canada — 29
–This card is typical of many in this collection, as it is a photograph which has been manually colored for printing, as well as having some artistic work done in the background to enhance the sky.
The car visible in the image indicates this is likely from the 1940s.