Stone Arch Bridge

Located below St. Anthony Falls in downtown Minneapolis, this large bridge crosses the Mississippi River and is an icon in the City of Minneapolis and the State of Minnesota. As the James J. Hill and the St. Paul, Minneapolis & Manitoba Railway expanded their network across Minnesota, a new crossing of the Mississippi River at Minneapolis was desired to reach the passenger terminal. By the late 1870s, preliminary plans were made to construct an iron bridge above St. Anthony Falls. Col. Charles C. Smith would be hired to design the new bridge. Smith quickly realized that constructing the new bridge above St. Anthony Falls would likely destabilize and erode the falls. In response, a large stone arch bridge was proposed, with the east abutment located parallel to the river below St. Anthony Falls. The east end of the bridge was required to be parallel to the river to reach the passenger terminal.

Construction began on the bridge in 1881, and was completed in 1883. Charles C. Smith oversaw the construction, while Edward Darragh was the contractor. The new bridge featured 23 spans of varying size, constructed of limestone quarried at Kasota, Minnesota and Stone City, Iowa. Granite was used for the piers and foundations, and was quarried at Sauk Rapids, Minnesota. Marble used for the deck and parapet walls was quarried at Bridgeport, Wisconsin. In total, 100,000 tons of stone was used in the project. The bridge consisted of four 98-foot spans, fifteen 80-foot spans, one 71-foot span, two 45-foot spans and one 40-foot span. On the east end of the bridge, a 6-degree 817-foot curve was provided to reach the passenger terminal. The bridge was completed at a cost of approximately $650,000.

Since the initial construction, the bridge has seen numerous alterations. Between 1907 and 1910, transverse steel rods were installed between the spandrel walls, reinforcing the bridge and providing greater load capacity. The deck of the bridge would be widened in 1925, by trimming the parapet walls of the bridge. The St. Anthony Falls area had always been a puzzle for the Army Corp of Engineers, which sought to open the river to navigation further north in Minneapolis. Proposals in the 1930s included adding a truss span near the middle of the bridge, near the west end of the curve. By 1960, a plan was finalized to replace spans #13 and #14 (an 80-foot and 98-foot span) with a riveted 10-panel Warren deck truss. These alterations were made in 1962. Further alterations were made after the flood of 1965 damaged spans #6 and #7. These repairs consisted of repairing damaged stones, and placing a 30-inch concrete lining underneath the bridge. Additional stones were repaired with concrete at locations throughout the bridge. Further repairs were made in 1993, after the bridge had been abandoned and was to be converted to a trail.

In 1978, the American Society for Civil Engineers designated the bridge a National Historic Engineering Landmark, stating that “it is acknowledged to be one of the finest stone viaducts in the world, due to its massive masonry, lofty arches, and graceful curvature.” During the 1990s, the bridge would be purchased by the Minnesota Department of Transportation, and converted to a pedestrian trail. The bridge has become one of the most iconic railroad bridges in the Midwestern United States, and is often featured in photography of Minneapolis. As of 2023, plans are underway to repair the bridge again, repairing and replacing stones as needed. Work is planned to begin in 2024 and continue through 2026.

Large stone arch viaducts like this were relatively uncommon throughout the United States, due to the large amount of high quality stone needed to construct them, as well as the complicated and oftentimes dangerous construction process. Overall, the bridge appears to be in fair condition, although planned improvements should help extend the life of the bridge. The author has ranked this bridge as being nationally significant, due to the large scale implementation of a stone arch viaduct.