Anoka–Champlin Mississippi River Bridge

Constructed in 1884, the Anoka–Champlin Bridge 4380 was the first structural span of the Mississippi River between Anoka and Champlin. A 1920s renovation strengthened the bridge, replacing the original’s stone materials with steel.

The 1884 bridge consisted of four steel spans with a wooden deck measuring eighteen feet wide. One of the spans could rotate, allowing for the passage of steamboats and other large vessels. The bridge’s wood decking limited traffic capacity, and individuals received a fine of ten dollars if they crossed at a pace faster than a brisk walk.

After the advent of the automobile at the turn of the twentieth century, the bridge became inadequate. The U.S. War Department determined that in the event of a national crisis, it would prove too narrow and weak to support military vehicles, and would impede the swift flow of river traffic.

In 1926, engineers wrote proposals for a modern structure to replace the outdated and insufficient original. Until a new bridge could be completed, the State Highway Department set a definite load restriction of six tons and posted signs to that effect. But the signage, heavy fines, and even threats of criminal prosecution failed to deter drivers with excessive loads from inflicting damage on the bridge.

During the 1920s, concrete gained popularity as a material for bridge construction since it was cheaper than stone yet similar in its compressive strength; in 1929, a new bridge replaced the old steel structure. Designers used an arch form and encased steel to compensate for the concrete’s low tensile strength. Since it did not require painting, as steel did, the bridge was considered relatively low maintenance.

Construction workers built the Anoka–Champlin Bridge’s concrete arches using “falsework,” a term for scaffold and wooden forms used to pour concrete. This method proved time consuming, labor intensive, and expensive. In the 1950s, pre-stressed girders replaced this type of bridge construction.

In 1979, the bridge was added to the National Register of Historic Places. National Register historians called it “a fine representative of the open spandrel concrete arch bridge”—a well preserved example of the style that was popular in and around the Twin Cities in the late 1920s. Workers replaced the top half of the bridge, down to the arches, between 1998 and 1999. The reconstruction did not alter its historic designation.