Seventh Street–Black River Bridge facts for kids
Quick facts for kids |
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Seventh Street–Black River Bridge
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 Location in Michigan
Location in the United States
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| Location | Seventh St. over Black River, Port Huron, Michigan |
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| Area | less than one acre |
| Built | 1932 |
| Built by | Wisconsin Bridge and Iron Company, Willits Brothers |
| Architect | John Alexander Low Waddell |
| Architectural style | single-leaf trunnion bascule |
| MPS | Highway Bridges of Michigan MPS |
| NRHP reference No. | 00000045 |
| Added to NRHP | February 4, 2000 |
The Seventh Street–Black River Bridge is a special bridge in Port Huron, Michigan. It helps people cross the Black River on Seventh Street. This bridge was added to the National Register of Historic Places in 2000 because it's important. It's also the only bridge of its kind in Michigan that opens up with just one side moving.
Building a Special Bridge
The first bridge at this spot was built around 1875. By 1928, the city realized it was too small. Cars needed more space to drive safely across the river.
The city planned to raise money to build a new bridge. They needed about $240,000. But then the Great Depression happened, which was a very tough economic time. This caused delays until 1931.
In 1931, the city hired a famous bridge designer, John Alexander Low Waddell. He finished his plans by July of that year. Soon after, the old bridge was taken down to make way for the new one.
How the Bridge Was Built
The Willits Brothers company was hired first. They built the bottom part of the new bridge. This part was finished by early 1932.
Then, the Wisconsin Bridge and Iron Company built the top part. They started in late 1931 and brought the pieces to Port Huron in mid-1932. The bridge was completed and opened that year.
Over the years, the bridge has been updated several times. In 1962, the road surface was replaced. Major repairs happened in 1970, and more updates took place in the 1970s and 1990s. In 2009, the small house where the bridge operator works was rebuilt to look like the original. The bridge is still used by cars and people today.
What Makes the Bridge Special
The Seventh Street Bridge is a type called a "single-leaf bascule bridge." This means it has one large section, or "leaf," that lifts up. This leaf is 114 feet long.
To help lift the heavy leaf, there's a huge counterweight. This counterweight is made of 620 tons of concrete. It acts like a seesaw, balancing the weight of the bridge leaf. The bridge pivots on two strong supports called trunnions.
The road part of the bridge is 40 feet wide. It has sidewalks on both sides for people to walk. The entire bridge, from one end of the railing to the other, is about 565 feet long.
The road surface was originally made of wood. But in 1960, it was changed to a metal mesh system. This makes it stronger and more durable.
