The Mississippi River crossing at Lansing, Wisconsin, consists of the main channel Blackhawk Bridge, and four smaller bridges. This page focuses on the second bridge from Iowa, the fourth on the Wisconsin side of the crossing. Like the other smaller bridges in this crossing, the original 1931 wooden structure was destroyed on March 18, 1945 by heavy ice. The crossing sat idle until it was purchased by the states of Iowa and Wisconsin in 1953, the bridges rebuilt, and opened to the public again in 1957.

The Big Slough bridge is built over an especially deep channel of the Mississippi River. The concrete piers extend over 30 feet below the waterline. It is reported that larger drilling equipment had to be brought in to sink the pilings for this bridge as compared to the other bridges on this river crossing.