Ever since Marquette and Joliet made the trek between the Fox River and Wisconsin River, the dream of a canal connecting the two major waterways teased scientific and commercial powers. After all, a canal between the two rivers would connect the Great Lakes to the Mississippi River system and therefore, to the Gulf of Mexico. (The waterways would eventually be connected through the Chicago River and Cal-Sag Canal in Illinois.)
The dream did not start to come to fruition until 1837 when the Portage Canal Company began to dig a canal by hand. The marshy land proved to be a formibable obstacle and the project was abandoned.
A second attempt to dig a canal began in 1849 but resulted in a narrow canal that wasn't suitable for anything larger than a canoe. The Corps of Engineers stepped in and completed a usable canal, including a lock to raise Fox traffic to the level of the Wisconsin, in 1876.
Starting in 1926, the lock was rebuilt (completed in 1928) including steel lock doors built by Lakeside Steel and Iron in Milwaukee. It is reported to be the first steel and concrete lock on the Fox River.
However, the canal was facing competition from active railroads, automobiles and trucks. Pleasure craft continued to use the canal until 1951 when the lock on the Fox River end was bulldozed in. Shortly afterwards, the Wisconsin River lock was sealed and the canal ended its useful life. In 1961, control of the canal passed from the Corps of Engineers to the State of Wisconsin. As you can see from the photos of the canal on the Fox River end, the state has done nothing with the canal.
A local group of enthusiasts, the Portage Canal Society is attempting to restore the canal to its appearance in the glory days of canals. In 1977, the canal was placed on the NRHP. The Wisconsin River end of the canal was restored in 1983 with funding by the City of Portage and using Block Grants and in 2006, the lock was restored. (It appears that a new lock door was installed during this restoration.)
Since the closure of the canal, a levee has been built along the Wisconsin River, something that would have to be overcome for the historic canal to connect the two great rivers once again.