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The United States has some of the longest tunnels in the world.

The tunnels are used for different purposes in the states based on where they are located. The longest tunnels in the USA are the Delaware Aqueduct, Cascade Tunnel, Anton Anderson Tunnel, Brooklyn Battery Tunnel, Eisenhower Tunnel, Holland Tunnel, Ted Williams Tunnel, Lincoln Tunnel, Baltimore Harbor Tunnel, and Hamptons Road Bridge Tunnel.

Top 9 Longest Tunnels in the US - 137 Kilometers
Top 9 Longest Tunnels In The US

How Many Tunnels Are There in the United States?

According to a Federal Highway Administration report from 2023, there are 562 road tunnels around the United States.

However, these sophisticated underground structures, which frequently require years of heavy-duty construction and advanced engineering, are used for more than just vehicle traffic.

They can also function as miles-long corridors for humans and trains, as well as water conveyance for consumption and hydroelectric power. Explore the fascinating history of the six tunnels listed below, which are among the longest in America.

What is the Longest Tunnel in the United States?

The Delaware Aqueduct is part of New York City's water supply system. It was built between 1939 and 1945 and transports approximately half of New York City's water supply.

The Delaware Aqueduct is the world's longest tunnel, measuring 137 kilometers long and 4.1 meters wide.

It is located in the northeastern United States, passing through New York, New Jersey, and Pennsylvania.

The tunnel transports drinking water from the Rondout, Cannonsville, Neversink, and Pepacton reservoirs on the Hudson River's west bank.

Top 9 Longest Tunnels In The US

1. Delaware Aqueduct

Length: 137 kilometers

The Delaware Aqueduct, built between 1939 and 1944, is the longest tunnel of any kind in the United States and the world's longest water supply tunnel.

This circular, concrete-lined tunnel, which measures 13.5 to 19.5 feet in diameter, is made up of three independent pressure tunnels that are dug through bedrock at underground depths ranging from 300 to 1,550 feet.

The tunnel transports water 85 miles from reservoirs on the Hudson River's west bank to Hillview Reservoir in Yonkers, just north of New York City. On any given day, the Delaware Aqueduct delivers up to 600 billion gallons of water to New York City. This is about half of the city's daily supply.

The reservoirs that supply the aqueduct, located in the Catskill Mountains' foothills, are available for pleasure. Non-motorized boating is allowed on the Cannonsville, Neversink, and Pepacton reservoirs, with Neversink notable for its seasonal fishing. These peaceful bodies of water are crucial habitats for bald eagles, with some of the greatest nesting populations in New York state.

2. Cascade Tunnel

Top 9 Longest Tunnels in the US - 137 Kilometers

Length: 12.6 km

The Cascade Tunnel refers to two railroad tunnels built by the Great Northern Railway. The original tunnel and its replacement are located in the northwest United States, in Washington's Cascade Range.

It was the longest railroad tunnel in the Americas until 1989, connecting Berne in Chelan County to Scenic Hot Springs in King County on the west.

The first tunnel, which was 2.63 miles (4.23 kilometers) long, opened in 1900. It was abandoned in 1929, after the new, longer, and lower tunnel was completed.

The current tunnel, which is 7.8 miles (12.6 kilometers) long, began in early 1929. Between Skykomish and Wenatchee, the new line was electrified for 72.9 route miles (117.3 km) or 93.2 route miles (150.0 km).

It is part of the BNSF Scenic Subdivision that connects Seattle and Wenatchee, with Amtrak's Empire Builder passing through it.

3. Hampton Roads Bridge-Tunnel

Length: 5.6km

The Hampton Roads Bridge Tunnel, measuring 3.5 miles (5.6 kilometers), is one of the longest tunnels in the United States. It began in 1957 and is part of the 3.5-mile Hampton Roads crossing.

This tunnel has four lanes, two eastbound and two westbound, and runs beneath the main shipping channels for Hampton Roads Harbor in southeastern Virginia, USA.

This tunnel connects the historic Phoebus neighborhood of Hampton, near Fort Monroe on the Virginia Peninsula, to Willoughby Spit in Norfolk, South Hampton Roads.

The bridge-tunnel was originally designated as State Route 168 (SR 168) and US 60. It was later given the I-64 designation when the second section opened in 1976.

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4. Anton Anderson Tunnel

Length: 4.18km

The Anton Anderson Memorial Tunnel is the second-longest in the United States (4.18). The Anton Anderson Memorial Tunnel is located near Whittier, Alaska. The tunnel is 2.5 miles long and takes 6.5 minutes to pass through.

This tunnel was excavated through a mountain for both highway and railroad traffic, making it the nation's longest dual-use tunnel. Computers keep an eye on traffic flow in the one-lane Anton Anderson Memorial Tunnel to prevent trains and vehicles from passing through at the same time.

5. Brooklyn-Battery Tunnel

Top 9 Longest Tunnels in the US - 137 Kilometers

Length: 2.78km

The Brooklyn Battery Tunnel, currently the second-longest tunnel in the United States, has been in operation in the New York area for more than 70 years. This tunnel, which connects populous areas such as Brooklyn and Manhattan, has four lanes.

The Brooklyn Battery Tunnel is approximately 1.73 miles long and is the longest underwater traffic tunnel on the continent. It is operated by MTA Bridges and Tunnels and charges tolls ranging from $6.80 to $8.50.

6. Eisenhower Tunnel

Top 9 Longest Tunnels in the US - 137 Kilometers

Length: 2.7km

The Eisenhower-Johnson Memorial Tunnel, sometimes known as the Eisenhower Tunnel, is one of the longest tunnels in the United States. To begin, at a height of more than 11,000 feet, this Colorado-based tunnel is the world's highest-elevated road tunnel.

Eisenhower Tunnel, in Denver, carries I-70 and averages over 32,000 vehicles each day. The tunnel was first opened in 1973, but exclusively for westbound traffic. Later, in 1979, it was completely open to both eastbound and westbound traffic.

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7. Holland Tunnel

Length: 2.6km

This tunnel, located beneath the Hudson River, is the second-longest in the New York area, connecting New York and New Jersey. The Holland Tunnel is a four-lane tunnel that connects Interstates 78 and 39. It is easily one of the longest tunnels in the United States, measuring 1.62 miles.

Furthermore, the Holland Tunnel, which opened in 1927, is one of the country's oldest road tunnels.

8. Ted Williams Tunnel

Length: 2.57km

Ted Williams is one of the longest tunnels in the United States, measuring 1.6 miles. This tunnel, an extension of I-90, is located in Boston, Massachusetts. This tunnel opened in 1995 and is still operational today. The tunnel has a speed limit of 40 mph and requires a $3.50 toll when entering South Boston (westbound only).

9. Lincoln Tunnel

Top 9 Longest Tunnels in the US - 137 Kilometers

Length: 2.4km

The Lincoln Tunnel, located under the Hudson River, connects New Jersey and New York. It stretches 1.5 miles and is the third-longest traffic tunnel in the area. This is one of New York's most iconic traffic destinations, having originated on Route 495.

But what truly distinguishes the Lincoln Tunnel is its three distinct tunnels, were opened in 1937, 1945, and 1957, respectively. Furthermore, the Lincoln Tunnel has one of the highest daily traffic counts in the United States, with over 100,000 automobiles.


Tunnels serve a variety of purposes, and the United States has some unusual examples. Tunnels can be built underwater to provide underwater vehicular transportation or to supply large amounts of water.

The United States is home to nearly every type of these tunnels. In truth, the United States has been building tunnels since the beginning of railroad development, and there are currently several dual-use tunnels around the country.

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