Iron County Heritage Trail - Historic Bridges

Historic Bridges

There are six bridges along current or former sections of US 2 that MDOT has added to its listing of Michigan's Historic Bridges; two of these are also listed on the National Register of Historic Places (NRHP). A third bridge added to the NRHP in late 2012 has not been added to MDOT's listing however. The first of these historic bridges is the crossing of the Iron River, which has since been bypassed by a new bridge. The original structure, dating to 1918, is a 55-foot-long (17 m) spandrel arch span that was built by the MSHD as Trunk Line Bridge No. 191. The structure was listed on the NRHP on December 9, 1999, for its architectural and engineering significance.

In December 2012, the National Park Service approved the listing of the Upper Twin Falls Bridge that crosses the Menominee River northwest of Iron Mountain. The structure is a single-span, pin-connected, camelback, through-truss bridge, and it is the only known example of its type in Michigan. It was built between 1909 and 1910 because the Twin Falls Power Dam would flood an existing river crossing. The span cost $5,106, paid equally by Dickinson and Florence counties. Until the 1930s, the Upper Twin Falls Bridge carried US 2 across the Menominee River. In 1934, a new bridge was built about a mile downstream, and the highway was rerouted over the new span. The bridge closed to automobile traffic in September 1971, and the nomination process for inclusion on the National Register of Historic Places began in 2012.

In 2003, MDOT replaced the Sturgeon River Bridge in Waucedah Township, Dickinson County. As of October 2011, even though the old bridge was demolished and replaced, MDOT retained it on their historic bridge list. It was built in 1929.

Before 1983, US 2 used a different routing through Manistique and crossed the Manistique River on what is nicknamed the "Siphon Bridge". Built as a part of a raceway flume on the river, the water level is actually higher than the road surface. This produces a siphon effect, giving the bridge its nickname. The Manistique Pulp and Paper Company was organized in 1916 and needed a dam on the Manistique River to supply their mill. This dam would require a large section of the city to be flooded, and shallow river banks meant difficulties in any bridge construction. Instead of expensive dikes, a concrete tank was built lengthwise in the river bed; the sides of this tank provided man-made banks higher than the natural banks. The Michigan Works Progress Administration described the bridge as having "concrete bulkheads, formed by the side spans of the bridge, allow the mill to maintain the water level several feet above the roadbed." The Manistique Tourism Council stated: "At one time, the bridge itself was partially supported by the water that was atmospherically forced under it," and that the bridge has been featured in Ripley's Believe It or Not!. The eight-span structure is 294 feet (90 m) long.

The Cut River Bridge carries US 2 across the Cut River in Hendricks Township, Mackinac County. This structure was built during World War II but completion was delayed due to war-induced steel shortages. The span uses 888 short tons (793 long tons; 806 t) of structural steel to bridge the 641 feet (195 m) over the river and its gorge at a height of 147 feet (45 m) above the river. The Cut River Bridge is one of only two cantilevered deck truss bridges in the state. On either side of the bridge, there are picnic areas and trails down to the river.

Listed on the NRHP on December 17, 1999, the Mackinac Trail–Carp River Bridge carries H-63, the modern successor to US 2, over the Carp River north of St. Ignace. The bridge is another spandrel arch structure 60 feet (18 m) in length and built in 1920. Increasing traffic along Mackinac Trail prompted the MSHD to "widen its deck by five feet and install new guardrails in the 1929–1930 biennium" along with the addition of decorative retaining walls.

The last of the historic bridges along a former segment of US 2 is the structure carrying Ashmun Street (BS I‑75) over the Power Canal in Sault Ste. Marie. Built in 1934, it is one of only three steel arch bridges in the state. The 42-foot-wide (13 m) and 257-foot-long (78 m) structure is described by MDOT as "massive" with an "innovative" construction method: the previous structure was used as a falsework for the current bridge before removal.