Photo courtesy of MTU Archives Harry Reeder photographed the old Portage Lake swing bridge next to the new lift bridge, on Dec. 9, 1959, 11 days before the bridge opened to traffic.

HOUGHTON — This year marks the 65th anniversary of the Portage Lake Lift Bridge connecting Houghton and the Keweenaw Peninsula. Since it was first opened, on Dec. 20, 1959, the bridge’s role has changed significantly.

The bridge’s original purpose was to provide a connection between the Keweenaw Peninsula and the mainland. It was a critical link for efficiently moving billions of pounds of copper mined from peninsula.

“This region, cut off from the rest of the country by the canal,” states the Michigan Department of Transportation (MDOT), “provided the nation with native copper, which played a role in the U.S.’s industrial and technological advancement from the mid-1800s to mid-1900s. ”

By bridge replaced an older, smaller, slow moving, swing-type bridge that had become entirely inadequate for traffic by the early 1950s. Larger commercial trucks, as well as larger passenger vehicles, heavier traffic, and larger ships compelled the Army Corps of Engineers and the U.S. Defense Department to order MDOT to construct a new bridge.

The design of the lift bridge had to meet a difficult challenge: Accommodating the automobile, rail, and water traffic that converge between the communities of Houghton and Hancock, MDOT says. Designers came up with a double-deck bridge with the unique ability to be parked in an intermediate raised position. With the lower deck raised to street level, the bridge has a clearance of 35 feet for the waterway, allowing smaller boats to pass without a lift.

In designing the Portage Lake Bridge to carry heavy loads on both decks concurrently, the lift bridge had the heaviest lift span in the world at 4,584,000 pounds and spanning 260 feet.

The bridge, designed by the Chicago engineering firm Hazelet and Erdal, is a remarkable example of lift bridge technology, according to MDOT. Its middle section can be raised from a clearance of four feet above the water to 100 feet, allowing boats to pass underneath. This feature makes it the world’s heaviest and widest double-decked vertical-lift bridge. Constructed with over 35,000 tons of concrete and 7,000 tons of steel, the bridge replaced a narrow, 54-year-old swing bridge that had become a navigation hazard on the busy Keweenaw Waterway.

While many reports say construction of the bridge began in 1959, MDOT says it began in the winter 1957. It took a little more than two years of continuous activity to complete the project, with crews working through the winters.

The bridge is not only a Copper Country icon and a popular subject of photographs, it is an engineering marvel. On June 17, 2022, the Portage Lake Lift Bridge was officially dedicated as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers (ASCE).

The bridge has an overall length of 1,310′ with a lift span 260′ long, and twin steel towers 180′ high. When fully raised, the lift span provides a clearance of 104′ for shipping on Portage Lake, part of the Keweenaw Waterway it is a two-level bridge, with four highway lanes on the upper segment and a railroad track on the lower level.

At 4,584,000 pounds, built with more than 35,000 tons of concrete and 7,000 tons of steel, the bridge was the heaviest double-decked vertical-lift span in the world at the time of its construction in 1959. It was also the first bridge in the United States to use an intermediate lift span position.

In its earlier years, more than 40 trains crossed the bridge per day, most of them transporting materials to and from the copper mines in the area. As mining declined, then stopped in 1968, though, train traffic did, too. The last train to cross the bridge was in 1982.

During the first three days of November 1961, 22 bulk carriers went through the lift bridge, Lake Superior Magazine reported in 2013. However, as lake freighters increased in size, eventually, they became too large to navigate the Keweenaw Waterway, and today they circumnavigate the Keweenaw Peninsula.

But while trains no longer pass over the Portage Lake Lift Bridge, and freighters no long pass beneath it, it sees an average of 22,000 vehicles passing it daily, and still lifts for the Ranger III and sailboats, and remains the focus of the annual Bridgefest celebration.