The Highway 243 Bridge crosses the Saint Croix River at Osceola, Wisconsin. It provides a highway river crossing between WI-35 on the east side of the river and MN-95 on the west side of the river, two highways that parallel the Saint Croix. The road on the west side of the river is designated MN-243, a highway that runs a grand total of 1-1/4 miles. The road on the east side of the river, WI-243, is the shortest state trunk highway in Wisconsin.

The Saint Croix River is much more calm here than upstream at the US-8 Bridge. The river flows through a wide valley rather than being confined between walls of rock found upstream in the Taylor's Falls area. The channel is wide and shallow with a calm current. The result is a longer bridge that is built much lower to the river.

The Highway 243 bridge gained a bit fame after the I-35W bridge collapse in 2007 due to the bridge being one of the few remaining deck truss bridges in Minnesota. A deck truss bridge has a metal lattice work of cross members, with the roadway being built on top of the truss. The deck truss is considered to be an obsolete style of bridge. The reasons include being fracture critical (ie, non-redundant, which means that any one piece breaking can result in the entire bridge failing), they are very hard to inspect (the structure is under the road rather than above the road), they are easily damaged by road salt (which can leak though cracks in the deck and cause the steel to rust), and truss bridges are far more costly to maintain.

The Highway 243 bridge receives routine inspections every other year. An additional inspection was completed shortly after the I-35W disaster. The bridge is not considered to be deficient, so it is not being considered for replacement anytime soon. The bridge was closed, however, for a month in the Spring of 2010 for refurbishment. Highway 243 was repaved on both the Minnesota and Wisconsin side of the river as part of this project.

Bridge fan Jake Lennington alerted me to a book titled ‘Osceola A Village Chronicle Sesquicentennial 1844 1944’ that has a few photos of the old bridge that was replaced by the current deck truss bridge in 1953. The bridge consisted of a truss swing span on the Wisconsin side of the channel and a single through truss span on the Minnesota side of the river. It appears to have been a very light bridge, single lane, wood deck, and was braced mostly with cables and rods as opposed to beams. I do not know when the old bridge was built, but this construction style suggests that it was built as a wagon bridge prior to the establishment of the highway system in the 1920s. One of the photos in the book is dated 1910. A photo caption indicates that the through truss span failed and collapsed into the river in 1938, and was replaced with a new truss span. Even with this replacement span, the bridge still carried a 4 ton weight limit. The bridge abutment on the Wisconsin side of the river still exists, as does the road leading to the east side of the river. The roadway leading to the west end of the bridge is abandoned, but still visible on aerial photographs.

The photo above is a profile view of the Highway 243 bridge from a park located on the Minnesota side of the river just downstream from the river crossing.

The photo above is looking east down the length of the bridge deck towards Wisconsin. The photo below is looking southwest towards the upstream face of the Highway 243 bridge. Note that the water level is near the top of the bridge piers due to an unusual autumn flood in 2010.

These two photos are views of the east abutment of the old swing bridge that once crossed the Saint Croix River at this location. The photo above is looking west down the hill leading to the old bridge. The photo below is a closer view of the abutment.