While you may be familiar with the country's more famous bridges — such as the Brooklyn Bridge — there are many enormous ones that don't have that kind of name recognition, though they're equally impressive. Here are just six of the longest bridges in the United States.

Louisiana Highway 1 Bridge

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This concrete toll bridge opened in 2009 and is also known as the Gateway to the Gulf Expressway. It's approximately nine miles long, making it one of the longest bridges not just in the United States, but in the world. It spans across Louisiana's Bayou Lafourche, a 106-mile-long river providing drinking water to over 300,000 people. Along with LA 3090, Louisiana Highway One provides one of the only ways to access Port Fourchon by land.

If you didn't think this bridge was long enough already, the LA 1 Improvement Project wants to expand it by nine more miles. Under this project, the bridge would ultimately reach Louisiana's Golden Meadow. The goal is to provide better evacuation routes to residents and local businesses when Louisiana experiences hurricanes or floods. The expanded bridge would also boost the economy by making local port towns more accessible to tourists and fishers.

Bonnet Carré Spillway Bridge

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This bridge is over ten miles long and carries Interstate 10. It spans Lake Pontchartrain, the LaBranche Wetlands, part of the St. John the Baptist Parishes, and, as its name suggests, the Bonnet Carré Spillway in Louisiana.

This spillway is a vital part of the Louisiana landscape. It helps to prevent the Mississippi River from flooding, reduces the river current's speed, and prevents local levees from becoming overwhelmed. This structure has only been opened 12 times since it was completed in 1931. The huge bridge spanning across the top of it was constructed several decades later, in 1972.

Chesapeake Bay Bridge-Tunnel

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Shore to shore, the Chesapeake Bay Bridge-Tunnel spans a spectacular 17.6 miles. It was opened in 1964, and by 1965 it had been designated as "One of Seven Engineering Wonders of the Modern World." It was also given the award for "Outstanding Engineering Achievement" by the American Society of Civil Engineers.

This bridge connects the Delmarva Peninsula with southeastern Virginia, spanning across open waters around the Chesapeake Bay and the Atlantic Ocean. It offers an incredible amount of convenience, cutting 95 miles off the trip between Wilmington, Delaware, and Virginia Beach.

Even more impressive is the condition under which it was built; due to its location on the Atlantic Ocean, this bridge had to be constructed during hurricanes and other severe storms. In 1995, a parallel crossing project was built under these same dangerous conditions in order to make the bridge even safer and to meet the increasing traffic demands.

Atchafalaya Basin Bridge

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Sometimes called the Louisiana Airborne Memorial Bridge or the Swamp Expressway, the Atchafalaya Basin Bridge measures 18 miles long and stretches across the Atchafalaya Basin. This basin is the largest river swamp in the country, encapsulating approximately a million acres of land — more than the Florida Everglades. In fact, the word "Atchafalaya" derives from a Choctaw term and means "long river."

The bridge is a twin bridge, meaning that it consists of two roadways running parallel to one another. It opened in 1973, and since then has become one of the busiest bridges in the state. Driving along the Atchafalaya Basin Bridge, you might find yourself driving through the treetops — parts of the bridge were elevated in order to allow barges to sail underneath. This bridge also connects several rural bayou areas with the highway, making travel much more convenient.

Manchac Swamp Bridge

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If you're into ghost stories and impressive feats of engineering, you'll absolutely love the Manchac Swamp Bridge. The 22.8-mile-long bridge stretches across the Manchac Swamp — a place swimming with folklore and supernatural tales. According to legend, a voodoo princess began haunting the swamp after she died in 1915. She is said to have placed a curse on the surrounding area, causing hurricanes and dangerous storms. But she isn't alone in the swamp. She shares her space with a Rougarou, or a Cajun werewolf (and a lot of alligators).

Just over 2,000 people travel across this area every day. The bridge carries about a third of I-55 across swampland. Due to its location, it was incredibly expensive to build. In order to ensure its stability, each concrete leg of the bridge had to be planted more than 250 feet into the swamp — this means that every single mile of the bridge cost $7 million to build.

Lake Pontchartrain Causeway

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At nearly 24 miles in length, the Lake Pontchartrain Causeway is the world's longest bridge across water — it was even recognized by the Guinness Book of World Records in 1969. You should avoid this bridge if you have any sort of fear of heights or water; once you get far enough onto it, there is a portion of the bridge where you completely lose sight of land in all directions. Drivers have been known to freeze up during this eight-mile stretch, suddenly feeling trapped and frightened. It is a common enough occurrence that local police know to simply escort these motorists back off the bridge.