Spanning Nations
On this day in history, work began on one of North America’s most impressive feats of cross-border engineering — the Sault Ste. Marie International Bridge. Stretching across the St. Marys River, this steel truss arch bridge connects Sault Ste. Marie, Michigan, and Sault Ste. Marie, Ontario — known affectionately as the “Twin Soos.” Before the bridge, the only way to cross between these two border towns was by ferry. The ferry service dated back to 1865. The dream of a fixed crossing took decades of planning. When construction finally began in 1960, the project moved swiftly toward a new era of connection.
The bridge was the result of a joint U.S.–Canadian effort. In the U.S., federal funding was approved because the bridge tied directly into the interstate highway system. It would serve as the northern terminus of I-75 and the end point of U.S. Bicycle Route 35. Ninety percent of the U.S. share was paid for with federal dollars, with the remaining portion covered through bonds. Contractors included Massman Construction Co. of Kansas City, MO, and Bethlehem Steel of Bethlehem, PA, who combined their expertise to tackle the challenging spans across the busy Soo Locks.
Finished
The finished structure — nearly 2.8 miles long — features two distinct main spans: a double-arch section on the U.S. side and a single-arch section on the Canadian side, linked by a long causeway. When it opened on October 31, 1962, the International Bridge instantly transformed travel, trade, and tourism between the two countries. For the steel, paper, and forest industries, it provided a faster, more efficient link. For everyday travelers, it was the gateway to cross-border shopping, cultural events, and international friendships.
Over the decades, the bridge has marked many milestones — from its 10 millionth crossing in 1975 to its 100 millionth in 2018. Annual traditions like the International Bridge Walk celebrate the special relationship between the Twin Soos, while major upgrades on both sides have kept the crossing safe, efficient, and welcoming. Today, it remains the tenth-busiest passenger crossing on the Canada–U.S. border and the only fixed link for hundreds of miles in either direction.
From its first steel beams rising over the river to the bustling traffic it carries today, the Sault Ste. Marie International Bridge is more than just a roadway. It’s a symbol of connection, cooperation, and the enduring bond between two communities — and two nations — that share more than just a name.
