Discover The Longest Bridge In Montana – A 2,437-Foot Behemoth

Updated: May 28, 2023
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Bridges can be true architectural wonders. Many people use them without really thinking about them, but the truth is that a lot goes into planning and designing a bridge. The ones that are well-planned can become true landmarks in their locations. Some bridges are very long. A lot of the time, these bridges cross large bodies of water. People on these bridges can enjoy exceptional views of their surroundings. If you live in Montana, you know that this state has some impressive examples of long bridged. But what is the longest bridge in Montana? Read on to find out!

The Longest Bridge In Montana

Lake Koocanusa Bridge
The beautiful Koocanusa Bridge is not only the longest but also the tallest bridge.

©Laurens Hoddenbagh/

Montana is home to more than 5,000 bridges. Afterall, Montana is the fourth largest state in the country. The Koocanusa Bridge is not only the longest but also the tallest bridge.

The Koocanusa Bridge goes all the way across Lake Koocanusa. It is 2,437 feet long. The bridge is also 270 feet tall above the lake, although this can vary with the water level in the reservoir. It connects Montana’s Highway 37 and Eastern Lincoln County with the western side of the reservoir.

There is a small Amish community on this side of the river, as well as many popular recreational spots on the western shore of the lake.

The bridge also gives people an option for a quick route into and out of the Yaak River Country in the northwest area of the forest when departing Eureka. While the majority of people drive across this bridge, it also has elevated sidewalks on both sides for pedestrians and cyclists.

Some people would say that the bridge doesn’t really go anywhere. It is true that there are relatively very few people living on the western side of the bridge. However, for those who need to get there, the bridge saves them a great deal of time. The alternative would be taking winding Forest Service roads around the lake, which would add about 50 miles to the trip.

Where Is The Koocanusa Bridge Located On A Map?

The Koocanusa Bridge crosses over Lake Koocanusa and is located near the towns of Rexford and Eureka which are in the northwest part of the state.

Montana is located in the Mountain West region in the northwest of the United States. It shares a border with Idaho to the west, Wyoming to the south, North Dakota and South Dakota to the east, and the following Canadian provinces to the North: Alberta, British Columbia, and Saskatchewan.

Reasons To Appreciate The Longest Bridge In Montana

The Continental Divide in Yellowstone National Park
The Kookanusa Bridge is part of the Pacific Northwest Trail, a route connecting Montana’s Continental Divide with the Olympic Peninsula, WA.


From this bridge, visitors can enjoy scenic views of the surrounding mountains and the large lake. This is particularly true for people who are biking or walking. It is adjacent to the Lake Koocanusa Scenic Byway.

Unlike the busy bridges in urban areas of Montana, this bridge is rarely, if ever, congested with traffic. This makes it possible to stop while driving and take a picture of the breathtaking view.

The Kookanusa Bridge is also a part of the Pacific Northwest National Scenic Trail, a 1,200-mile route that connects the Continental Divide of Montana with the Olympic Peninsula of Washington.

Not only do the bridge and lake offer a unique scenic drive, but also a variety of activities. There are many public campgrounds along the shores of the lake. One of them is Rocky Gorge, which is home to 120 campsites where people can park their recreational vehicles or pitch their tents.

There are other campgrounds that have boat ramps, swimming beaches, and other amenities as well. In addition, there is a former lookout tower on the western side of the lake that is often available for overnight rentals.

History Of The Longest Bridge In Montana

In the early 1970s, the Army Corps of Engineers constructed this bridge. It was designed by Morrison-Maierle, Inc. The bridge had a very specific purpose.

When officials made plans to build the Libby Dam on the Kootenai River, it was considered a good decision. After all, it would provide hydroelectric power and flood protection to the area.

However, it created an inconvenience for people who lived on the west side of the river. They would not be able to go to Eureka for shopping and other services easily. Now, they would have to drive a great deal of extra distance around the lake on Forest Service roads to get to Libby.

From the bridge to Yaak is approximately 41 miles. The distance between the bridge and West Kootenai is about a dozen miles.

In order to help the people on the west side, officials made a decision to build the Koocanusa Bridge. Because of its length, it required six truss spans on five piers. The bridge is also tied into bedrock on both ends. In 1972, the bridge won the “Most Beautiful Bridge” award from the American Institute of Steel Construction.

It was also very useful to the almost 200 West Kootenai residents who needed to be evacuated in September 2017. The Caribou Fire ravaged almost 20,000 acres of their land.

Animals Around The Longest Bridge In Montana

long-billed curlew
In addition to fish, there are plenty of animals that live around the lake, including long-billed curlews.

©Thomas Morris/

Lake Koocanusa is part of the aftermath of Libby Dam on the Kootenai River. The lake takes up about 29,000 acres and goes from the state of Montana up into Canada. There is quite a bit of diversity here in terms of wildlife.

Anyone who is interested in fishing will find a variety of fish. These include whitefish, bull trout, cutthroat trout (the state fish of Montana), kokanee salmon, brook trout, rainbow trout, yellow perch, pumpkinseed, pike, and bass.

The lake is very large, and most of these fish live closer to the center. Anglers need a motorboat to reach the best spots.

It’s important to keep in mind that there are occasional drawdowns of the reservoir that are necessary for power production. When this happens, the water levels of the lake can be very low, which can make boating and fishing somewhat difficult.

In addition to fish, there are plenty of animals that live around the lake. They rely on the wetlands, grasslands, and streams to survive.

Many elk and deer inhabit these areas. There are also turtles, long-billed curlews, and badgers. Humans are encouraged to avoid poaching these animals, as their populations are vulnerable.

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