Stone Arch Bridge in Minnesota

The Curve That Kept St. Anthony Falls Flowing: The Origins of the Stone Arch Bridge’s Odd Angle

The historic Stone Arch Bridge is one of Minneapolis’ most iconic landmarks. Spanning the Mississippi River with its elegant arched design, the bridge captures the eye of visitors and locals alike.

But have you ever wondered why this 136-year-old bridge crosses the river at such an odd diagonal angle? The story behind its unique orientation is a fascinating tale of ingenious engineering and careful planning.

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Overcoming a Railroad Conundrum

In the 1880s, Minneapolis faced a significant railroad problem. With no efficient way to bring goods and passengers into downtown from the rail tracks on the east side of the river, the city turned to James J. Hill, owner of the main rail connection between Minneapolis and St. Paul, for a solution.

The goal was to construct a Union Depot near the intersection of Nicollet and Hennepin avenues, allowing trains to easily access the heart of the city.

Hill initially considered a more direct route with a new bridge across Nicollet Island. However, his engineer, Col. Charles C. Smith, had reservations about disrupting the sandstone riverbed above St. Anthony Falls, which could potentially alter the water power fueling the city’s industry.

Train on stone arch bridge
Train crossing the Stone Arch Bridge, with the milling district in the background, c.1910. | Minnesota Historical Society

An Ingenious Angled Design

To mitigate the risk of catastrophic erosion and ice jams, Smith devised an ingenious solution: construct the bridge below the falls, just upstream from where Hill’s tracks ended near present-day Dinkytown.

By crossing the river at a diagonal angle, with a 6-degree curve at one end, trains could efficiently travel to and from the proposed Union Depot while minimizing disruption to the riverbed.

Speed and Permanence in Mind

Unlike the fragile timber railroad bridges of the era that required trains to crawl across, Hill wanted a permanent structure that could accommodate trains steaming over at full speed.

The Stone Arch Bridge’s sturdy design and gentle curve allowed for efficient, high-speed rail transportation, a significant advantage in an era when speed was paramount.

Stone Arch bridge under contrusction
Stone Arch Bridge and workers as the bridge nears completion in 1883. | Public Domain

Legacy of Innovation

The Union Depot opened in 1885, and the Stone Arch Bridge quickly became an integral part of Minneapolis’ transportation infrastructure.

Its unique angle, born out of a desire to preserve the natural environment while solving a logistical challenge, has endured as a testament to the innovative spirit of the city’s early engineers.

Today, the Stone Arch Bridge stands as a beloved landmark, its diagonal orientation a reminder of the ingenuity and foresight that went into its construction over a century ago.

As visitors and residents alike marvel at its elegant arches and picturesque views, they can appreciate the bridge’s unique angle as a symbol of Minneapolis’ rich history and engineering prowess.

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