The 10 Longest Bridges in the United States

March 12, 2024

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Chesapeake Bay Bridge

Bridges are an important part of commuter journeys up and down the country and an essential trade route. Some bridges are designed for foot traffic across a small lake, while others stretch for miles across open water and carry thousands of trucks and cars each day.

We’ve rounded up the ten longest bridges in the United States. We’ll take a look at where these massive structures are and their history. Let’s jump in!

1. Lake Pontchartrain Causeway

Length: 23.9 miles (38.4 km)
Location: Louisiana
Opened: 1956 (southbound)

Not only is the Lake Pontchartrain Causeway the longest bridge in the United States, but the bridge also has the longest continuous span over water in the world. The causeway consists of two parallel bridges that cross Lake Pontchartrain in southeastern Louisiana.

The Lake Pontchartrain Causeway is supported by 9,500 concrete pilings (posts that support the bridge’s structure). Louisiana soil has soft clay and silts, which means pilings must be driven deep into the ground before they meet significant resistance. Engineers used large, prestressed hollow piles that could withstand the force needed to drive them deep into the ground.

In 2013, the bridge was listed as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers. This designation is reserved for structures that have historical civil engineering significance to the US and the world.

The bridge took just 14 months to build. It was the first time mass production, and assembly lines were used to construct a bridge in the US.

2. Manchac Swamp Bridge

Length: 22.8 miles (36.7 km)
Location: Louisiana
Opened: 1979

Measuring an incredible 22.8 miles long, the Manchac Swamp Bridge is the second-longest bridge in the US and the longest bridge on the Interstate Highway System. It’s also claimed that the bridge could be the world’s longest toll-free road bridge.

The bridge runs over the Manchac Swamp in Louisiana. It comprises one-third of Interstate 55’s approximate 66 miles (106 km) portion in the state. To support the lengthy bridge, its piles were driven 250 feet (76 m) into the swamp. The construction cost was approximately $7 million per mile, equating to roughly $21.4 million per mile in 2021.

Manchac Swamp Bridge is split into two sections. The northern section connects Starder and North Pass, while the southern section connects Manchac to Galva. The two bridges, plus the gap in between, measure approximately 312 feet (95 m).

3. Atchafalaya Basin Bridge (Louisiana Airborne Memorial Bridge)

Length: 18.2 miles (29.3 km)
Location: Louisiana
Opened: 1973

Louisiana is certainly fond of its long bridges! The Atchafalaya Basin Bridge, yet another bridge in the Pelican State, is the third-longest bridge in the United States. It features two parallel bridges that run between Baton Rouge and Lafayette.

If you want to leave the bridge, you’ve got two chances. The Whiskey Bay (Louisiana Highway 975) and Butte La Rose (LA 3177) are the only two exits on the entire bridge.

Accidents are fairly common on the Atchafalaya Basin Bridge because it doesn’t have any shoulders. In 1999, then-governor Mike Foster lowered the bridge’s speed limit from 70 mph to 60 mph to try and reduce the number of accidents.

4. Chesapeake Bay Bridge-Tunnel

Length: 15 miles (24.1 km)
Location: Virginia
Opened: 1964

Ferries had been crossing the Chesapeake Bay for around 350 years. However, by 1964, the increase in cars led to the construction of the Chesapeake Bay Bridge-Tunnel. This 15-mile (24.1 km) long bridge is one of only 14 bridge–tunnel systems in the world.

The bridge-tunnel took 42 months to construct. At the time, it was called the Lucius J. Kellam, Jr. Bridge-Tunnel in honor of the chairman of the Chesapeake Bay Ferry Commission, who helped lead the project to fruition.

Not only is the Chesapeake Bay Bridge-Tunnel used as a route to get from A to Z, but it also acts as an attraction itself. Many birds have made a home on the bridge and its artificial islands (which are used as rest stops). The island used to have a scenic overlook at the southern end of the bridge before it was moved to the northern end of the bridge.

5. I-10 Bonnet Carré Spillway Bridge

Length: 11 miles (17.7 km)
Location: Louisiana
Opened: 1972

The I-10 Bonnet Carré Spillway Bridge stretches 11 miles through southeastern Louisiana between Baton Rouge and New Orleans.

The twin concrete trestle bridge passes over the Bonnet Carré Spillway, Lake Pontchartrain, and LaBranche Wetlands. It has two parallel concrete trestle bridges, each with two lanes of the Interstate 10, a major transcontinental Interstate.

I-10 Bonnet Carré Spillway Bridge was built after a flood in 1927 devastated 27,000 sq miles of the lower Mississippi Valley. To prevent flooding, the spillway diverts any excess water from the Mississippi River into Lake Pontchartrain. The spillway is not only key to flood protection for the Mississippi Valley, but it also carries Interstate 10 over the water.

6. Louisiana Highway 1 Bridge

Length: 8.3 miles (13.3 km)
Location: Louisiana
Opened: 2009

This 8.3 mile long bridge is the sixth-longest bridge in the US and the fifth-longest in Louisiana. It carries the Louisiana Highway 1 above the Bayou Lafourche and marshes in the southern region of the state.

Louisiana Highway 1 Bridge is a toll bridge. From 1 January 2023, two-axel vehicles must pay a toll of $4.50. Three axel vehicles must pay $6.50, four axel vehicles must pay $8.75, and five axel vehicles must pay $17.50.

The bridge was opened in 2009 and is the newest addition on the list. Phase 1 of the construction cost a whopping $371.6 million, but it doesn’t stop there. Plans have been made to expand the bridge northward to Golden Meadow, which sits further up the Bayou Lafourche.

7. Jubilee Parkway

Length: 8 miles (12.9 km)
Location: Alabama
Opened: 1978

Jubilee Parkway stretches eight miles (12.9 km) over Mobile Bay in Alabama. The bridge is colloquially called ‘Bayway’. It consists of two parallel concrete viaduct bridges with two lanes each. However, the Alabama Department of Transportation (ALDOT) has planned to extend the bridge to eight lanes since 2001, although the plans have not been formalized yet.

On 20 March 1995, one of the country’s biggest multi-vehicle collisions took place on the Jubilee Parkway. It was caused by fog from Mobile Bay, leading to low bridge visibility. The incident involved 200 vehicles; one person was killed, and over 90 others were injured.

Despite what you may think, the bridge has no link to royalty. It was actually named after the jubilee phenomenon, a natural event that occurs in Mobile Bay. Water in the bay rises while oxygen levels decrease. Fish become trapped in shallow waters, which attracts a large number of residents and tourists who harvest them.

8. San Mateo-Hayward Bridge

Length: 7 miles (11.3 km)
Location: California
Opened: 1967

Stretching seven miles (11.3 km) from the San Francisco Peninsula to the Eastern Gulf, the San Mateo-Hayward Bridge is the eighth-longest bridge in the US. It carries six lanes of State Route 92 over San Francisco Bay from Foster City on the bridge’s western end to the city of Hayward at the bridge’s eastern end.

The original bridge (the San Francisco Bay Toll Bridge) was built in 1929. However, by the 1950s, the bridge couldn’t cope with the ever-increasing traffic. A new bridge was opened in 1967 at a cost of $70 million. In 2003, the bridge was widened, and an additional three lanes were added for a cost of $200 million.

Vehicles crossing the San Mateo-Hayward Bridge must pay a toll (currently $7 per passenger car). Carpool vehicles (carrying three or more people), motorcycles, and clean-air vehicles pay a discounted rate of $3.50 during peak traffic hours.

9. Seven Mile Bridge

Length: 6.8 miles (10.9 km)
Location: Florida
Opened: 1982

Not to be pedantic, but the Seven Mile Bridge actually measures 6.8 miles (10.9 km) long! The bridge was opened in 1982, although there had been a bridge in the location since the early 1900s as part of the Florida East Coast Railway’s Key West Extension. When the railroad was wrecked by the Labor Day Hurricane of 1935, it was sold to the government and refurbished for motoring use. It connects the Florida Keys, a coral cay archipelago off Florida’s southern coast.

The bridge carries two lanes of US Highway 1 across the Moser Channel. It connects Knight’s Key in the city of Marathon to Little Duck Key in the Lower Keys. Not only is the bridge used by vehicles, but it also carries fiber optic cables to and from the Lower Keys and water supplies.

Seven Mile Bridge was been closed and restored periodically. In 2008, the unsupported sections of the bridge were closed because they were beginning to sag. Several years later, in 2017, the pedestrian section was closed to undergo extensive repairs before reopening in early 2022.

10. General W.K. Wilson Jr. Bridge

Length: 6.1 miles (9.8 km)
Location: Alabama
Opened: 1980

With a nickname like the ‘Dolly Parton Bridge’, you’d be forgiven for thinking the General W.K. Wilson Jr. Bridge is brightly colored and covered in rhinestones. Sadly, that’s not the case — the bridge’s nickname comes from its two arches that look like… well, you get the idea.

The General W.K. Wilson Jr. Bridge carries four lanes of Interstate 65 over the Mobile-Tensaw River Delta in Alabama. It measures just over six miles (9.8 km), while the highest point of the arch is an impressive 125 feet (38 m) above the water below.

In 2014, the bridge sustained damage after two trucks collided. The heat from the explosion damaged the concrete deck, which took several months to be repaired. The two northbound lanes were completely closed during the repair works, so one of the two southbound lanes was divided into one southbound and one northbound lane.

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