The Winnebago River Bridge was a historic structure located north of Mason City, Iowa, United States. The span carried U.S. Route 65 over the Winnebago River for 122 feet (37 m). This is the second span at this location. The stone abutments from the previous bridge were utilized in this one. They were sheathed in concrete by the Concrete Engineering Company, and William Henkel of Mason City constructed the bridge. It is composed of three concrete spans with a 70 feet (21 m) center span cantilevered from shorter anchor spans. It was listed on the National Register of Historic Places in 1998. A second span has subsequently been built to the east in 1969.

The bridge was replaced in 2009.

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• Historic American Engineering Record (HAER) No. IA-78, "Winnebago River Bridge, Spanning Winnebago River at U.S. Highway 65, Mason City, Cerro Gordo County, IA", 8 photos, 18 data pages, 1 photo caption page