The USA doesn't do megaprojects by halves, investing years – sometimes even decades – of time and billions of dollars in to the development of bridges, railroads, airports, and more.

From icons of infrastructure such as

 the Golden Gate Bridge to modern marvels such as the replacement Yankee Stadium, read on to discover America's most expensive public and private construction works of all time.

We'll also reveal how much they would cost to build in today's money, with all dollar amounts in US dollars. 

Measuring over 4,200ft (1,280m) long, San Francisco's Golden Gate Bridge was completed in 1937 and promptly became the world's longest suspension bridge, a title that it retained until 1964.

Famous around the world, this amazing feat of engineering cost a total of $35 million in 1937, which equates to $746 million today. 

With the exception of the Sausalito Lateral approach road (today known as Alexander Avenue), which was built as a federal Works Progress Administration (WPA) project, there was no state or federal funding involved in building the Golden Gate Bridge.

Another construction triumph of the Depression Era, the Hoover Dam was built between 1931 and 1936 at a cost of $49 million.

Its power plant and generators cost an additional $71 million, resulting in a grand total of $120 million. That's around $2.7 billion in today's money.

As well as providing tens of thousands of jobs over the decades, the colossal dam is a key flood control safeguard and a major supplier of hydroelectric power in the region. In fact, the sale of electrical power generated by the Hoover Dam had paid back its construction cost, complete with interest, by 1987.

Part of the Central Florida Beltway, the Wekiva Parkway (also known as Florida State Road 429) is slated for completion later this year at a total projected cost of $1.6 billion.

The 25-mile-long (40km) highway passes through the environmentally sensitive Wekiva River Basin, adding to the complexity and expense of the work. Most of the project will be financed courtesy of tolls on the new highway. 

Extension 470, more commonly known as E-470, is a 47-mile-long (76km) toll road that curves around the eastern edge of the Denver metropolitan area in Colorado. 

Built in sections and completed in 2003, E-470 cost a total of $1.5 billion, which works out at around $2.5 billion when adjusted for inflation.

It's one of the first privately built, owned, and operated toll roads in the US.

This extensive highway project focused on the reconstruction and widening of a 7-mile (11.6km) stretch of highway between Interstate 95 (I-95) between New Haven and Branford, Connecticut. By the time the work was finished in 2018, it had racked up a cost of $2.2 billion, which is about $2.8 billion (£2.3bn) today. 

The program also included building a new 10-lane Pearl Harbor Memorial Bridge over the Quinnipiac River. This was to replace the existing bridge, which dated back to the 1950s. 

The replacement Yankee Stadium in New York cost $2.3 billion to construct in 2009, making it the most expensive stadium ever built at the time.

Controversially, a hefty $1.2 billion of public money helped fund the project. Adjusting that for inflation, the stadium cost a total of $3.3 billion in today's dollars.

Measuring in at 7,710 feet (2,350m), the replacement Evergreen Point Floating Bridge is the longest floating bridge in the world.

Completed in 2016, the six-lane bridge carries State Route 520 across Lake Washington from Seattle to its eastern suburbs. This megaproject also included road widening to add high occupancy vehicle (HOV) lanes, improved bridge approaches, and other traffic infrastructure improvements.

The total package came to $4.5 billion, which is $5.6 billion when adjusted for inflation. 

The Alaska Highway was completed in 1942 – a remarkable achievement given that the US was at war at the time.

The final bill for the 1,700-mile (2,700km) highway was $138 million, the equivalent of $2.6 billion (£2bn) today. The gruelling project required a crew of more than 25,000 men to work seven days a week.

The largest highway infrastructure project in Florida's history, the I-4 Ultimate focused on improvements to a 21-mile-long (34km) stretch of Interstate 4 in the Orlando area.

The program included reconstructing 15 interchanges, building 53 new bridges, and replacing or widening another 87 bridges. It also introduced four express toll lanes. Work began in 2015 and finished in 2021, at a total cost of $2.9 billion (£2.4bn), or $3.3 billion (£2.7bn) today.

Completed in 1869, the First Transcontinental Railroad spanned 1,912 miles (3,077km), connecting America's rail network from Omaha, Nebraska, to Sacramento, California. 

Two companies took on this massive undertaking: the Union Pacific built the line westward and the Central Pacific worked eastward, with the two meeting in Utah.

Compensation included land rights and government bonds, meaning that there are no reliable figures for the exact cost of the railroad. One estimate puts the total at around $111.5 million, which is $2.5 billion today.

This ambitious project aimed to expand the US freight rail network across 13 states from Louisiana to New Jersey, covering around 2,500 miles (4,000km).

In a public-private partnership between the government and Norfolk Southern Railway, it also included expanding or building terminals in 11 markets, allowing rail freight to compete with the long-haul trucking services offered along nearby interstates and highways.

Cost estimates for the program were $2.5 billion (£2bn) when many of the initial terminals opened in 2012. That's $3.3 billion (£2.7bn) in 2023 terms.

With a length of 4,260ft (1,300m), the Verrazzano-Narrows Bridge snatched the Golden Gate's crown and became the longest suspension bridge in the world upon its completion in 1964. It held on to the title for 17 years before being usurped by the UK's Humber Bridge in 1981.

The Verrazzano-Narrows crossing, which connects Brooklyn and Staten Island while spanning New York Harbor, cost $305 million (£248m) to build, which is $3 billion (£2.4bn) when adjusted for inflation.

Also known as the Intercounty Connector, this 18-mile (29km) road project in Maryland was initially proposed back in 1969 but wasn't approved for construction until the early 2000s.

The tolled highway connects I-270 in Gaithersburg, Montgomery County, and US 1 in Laurel, Prince George's County. By the time the work was finished in 2014, it had cost $2.4 billion (£2bn), which is around $3.1 billion (£2.7bn) today.

Still under construction, this extension of Interstate 69 from Evansville to Indianapolis is a whopping 142 miles (235km) long.

Dubbed one of six "Corridors of the Future" in 2008, the sixth and final section is expected to be completed in 2024. The program's cost has grown to $4 billion (£3.3bn).

This wide-ranging expansion of Interstate 10 in Houston was carried out over a period of five years between 2003 and 2008, costing a total of $2.8 billion, or $4 billion when adjusted for inflation.

Increased traffic in the city meant that congestion on the roads was lasting for up to 11 hours a day, so a fix was badly needed. Major reconstruction work along a 12-mile (19km) section expanded the Katy Freeway to six general lanes in each direction, with two toll lanes.

One of the world’s largest drawbridges, the Woodrow Wilson Memorial Bridge (also referred to as the Woodrow Wilson Bridge) carries 12 lanes of traffic over the Potomac River between Alexandria, Virginia, and Oxon Hill, Maryland.

Plans for replacing the original bridge, which opened in 1961, had been in motion since the 1980s, although construction didn't begin until 2000. The new bridge opened to traffic in 2008 at a total cost of $2.4 billion, or $3.4 billion today.

LaGuardia once held the dubious honour of being ranked among the very worst of the USA's airports, with America's then-VP Joe Biden comparing it to arriving at "some third-world country" in 2014.

The following year, New York's then-governor Andrew Cuomo launched an ambitious overhaul of the NYC airport, plugging $8 billion into improving its terminals and facilities.

Two-thirds of the cost has been covered by private funding, with the work on the now-award-winning airport reaching completion in 2022. 

This complex megaproject included two new bridges (the East End Bridge and the Abraham Lincoln Bridge), as well as the construction of roadways, freeway interchanges, a tunnel, and other facilities that connect Indiana and Kentucky over the Ohio River.

Shared across both states, all of this new infrastructure was delivered in two programs, with Indiana leading the East End Crossing and Kentucky leading the Downtown Crossing project. Both were completed by 2016 for a grand total of $2.8 billion (£2.3 bn), which is $3.6 billion (£2.9 bn) today.

Officially the tallest building in the Western Hemisphere, One World Trade Center is the principal building in the rebuilt World Trade complex in New York City.

Standing at 1,776ft (540m) tall – this is symbolic as the Declaration of Independence was signed in 1776 – work on the skyscraper was completed in 2014 at a cost of around $3.8 billion (£3.1bn), which is $4.9 billion (£4bn) today.

Owned by the Port Authority of New York and New Jersey, the reconstruction has been paid for by a combination of public funding and insurance money.

At a length of 1.7 miles (2.7km), this tunnel project was beset by problems ever since excavation work first began beneath Seattle in July 2013.

Almost immediately after the work commenced, it was stalled for two years after the tunnel boring machine – nicknamed "Bertha" and, at the time, the largest of its type in the world – needed repairs to its main bearing.

The estimated completion date for the work, which now operates as the State Route 99 tunnel, was shifted from 2015 to 2019. The total cost came to $3.3 billion (£2.7bn), or $4 billion (£3.3bn) when adjusted for inflation.

The Central Texas Turnpike project saw the construction of three toll roads (now known as the Austin Area Toll Roads) in Austin and along the Austin-San-Antonio corridor.

They opened to traffic in 2008 after six years of construction, with the work costing around $3.3 billion (£2.7bn). That's $4.7 billion (£3.8bn) with inflation.

This extension to the Silver Line in Washington, D.C., connected the city’s downtown with Dulles International Airport, adding a total of 11 new stations.

Construction took place in two phases, with the final grand opening of the 23-mile (37km) line taking place in 2022. The total project cost around $6 billion (£4.9bn), much of which has been funded by drivers on adjacent toll roads.

Replacing a section of the seismically unsound eastern span of the Bay Bridge was to become one of the most expensive public works projects in Californian history, setting the state back an eye-watering $6.5 billion (£5.3bn).

That's $8.6 billion (£7 billion) when adjusted for inflation – and significantly higher than the $250 million price tag that was originally attached to the work back in 1995.

Construction started in 2002 and wasn't completed until 2013.

Four different road projects make up the Pennsylvania Turnpike Commission’s Mon/Fayette Expressway, with three already completed.

Facing funding setbacks, the program has seen its last part delayed for a number of years. Although construction started in 2023 on the first section of the final and largest road, substantial completion is not scheduled until 2028.

According to 2019 estimates, the Commission has so far spent $1.9 billion (£1.4 bn), which is $2 billion (£1.6bn) with inflation factored in. The next phase is estimated to cost a further $1.3 billion (£1bn).

Plans for New York’s Second Avenue Subway date back to the 1920s. However, financial roadblocks throughout the 20th century reduced the 8.5-mile (14km) project into four phases.

Phase 1, which comprised of 1.8 miles (3km) of subway line and three stations, opened in 2017 at a cost of $4.5 billion (£3.7bn), or $5.6 billion (£4.6bn) today.

New York Governor Kathy Hochul announced this summer that Phase 2 will be moving forward imminently, extending the subway to 125th Street in Harlem.

New York’s East Side Access was the Metropolitan Transportation Authority’s (MTA) largest ever capital project. The work included the addition of 40 miles of new tracks to the Long Island Rail Road (LIRR) and the erection of a massive new terminal beneath Grand Central.

Construction began in 2001, with 2009 floated as the expected completion date. However, this came and went, with the project finally opening in 2023, having racked up a bill of nearly $12 billion (£10bn).

Work on the San Francisco’s Bay Area Rapid Transit (BART) rail system started in June 1964.

With a number of underground sections, the project included the construction of the underwater Transbay Tube, a 3.8-mile-long (6km) tunnel made up of 57 giant steel and concrete sections immersed beneath San Francisco Bay itself. 

The first section of the system went into operation in 1972 and reportedly carried 100,000 passengers across its 28 miles (45km) of track in just five days. As of the mid-1970s, it was estimated that it had cost $1.6 billion to build, which is around $12 billion today.

The Central Artery/Tunnel Project – nicknamed the "Big Dig" – replaced Boston’s tired six-lane elevated Central Artery with a 3.5-mile (5.6km) underground highway.

The work also included the construction of two bridges across the Charles River, as well as a number of new roads.

Needless to say, the project, which launched in 1991, was incredibly expensive and encountered several delays. The final bill topped a staggering $14.8 billion once the project wrapped in 2007, which is $21.9 billion in today's money.

The Trans-Alaska Pipeline system was built between 1974 and 1977 at a cost of $8 billion, making it the world's largest privately funded project at that time. In today's dollars, that's around $40.6 billion.

Crucial to the Alaskan economy, the 800-mile-long (1,300km) pipeline has been instrumental in facilitating the growth of the state's oil industry.

Now discover the 28 most expensive megaprojects in the world