The US is spending billions of dollars deepening port harbors to make room for 'mega' container ships that are only getting bigger

• Container ships more than doubled in size over the past decade to keep up with global trade.
• To make room for the 'mega' ships, Congress has allocated billions of dollars to deepen US ports.

The Ever Ace, the world's largest cargo ship, is as long as four football fields and can carry over 23,000 containers.

Container ships like this one have more than doubled in size over the past decade. While the massive vessels can hold more Amazon orders than you can imagine, the rapid growth presents a problem for US ports — the ships can't fit into most harbors.

In response, the Army Corp of Engineers has allocated billions of dollars to deepen ports across the US.

From Massachusetts to Alabama, officials say ports must accommodate supersized ship dimensions in order to remain competitive in global trade.

At The Port of New York and New Jersey, a $2.1 billion harbor-deepening project freed up access to "post-panamax" ships, the name for mega ships too large to travel through the Panama Canal.

The vessels' larger-than-life size may be contributing to the supply-chain crisis that's caused record-breaking backlogs at US ports, one expert told Insider.

"Part of the problem is the ships are double or triple the size of the ships we were seeing 10 or 15 years ago," Kip Louttit, executive director of the Marine Exchange of Southern California, said. "They take longer to unload. You need more trucks, more trains, more warehouses to put the cargo."

Proponents of harbor-deepening projects like New York's point to the benefits port economies have on local job markets. Other dredging proposals like North Carolina's $834 million Wilmington Harbor Navigation Improvement Project face pushback over environmental concerns.

Insider compiled a list of 10 harbor deepening project currently in progress and the reported budgets of each. Most projects receive both federal and state funding.

1. The Port of New York and New Jersey Harbor Deepening ($2.1 billion).

Touring the Port of New York and New Jersey.      Thomas Pallini/Insider

Source: US Army Corp of Engineers

2. The Charleston, South Carolina Harbor Deepening Project ($565 million).

Container ships at the Port of Charleston.      Glowimages

Source: South Carolina Ports

3. The Jacksonville, Florida Harbor Deepening Project ($484 million).

A worker stands on a crane, overlooking the docks at the Port of Jacksonville, Florida.      Jake Wyman

Source: Jacksonville Port Authority

4. Deepening and widening of the Port of Mobile, Alabama ($365.3 million).

Port of Houston      Getty

Source: US Senator Richard Shelby

5. Port of Virginia "Wider, Deeper, Safer" dredging project ($350 million).

Abstract Aerial Art

6. Boston, Massachusetts Harbor Deepening ($306.2 million).

A container ship weighing 89,954 gross tons and drawing 12 meters is unloaded at Boston harbor.      David L. Ryan/The Boston Globe via Getty Images

Source: US Army Corp of Engineers

7. The Mississippi River Ship Channel Dredging Project ($238 million).

Former US President George W. Bush gives a speech after touring the Port of New Orleans, 15 January 2002 in Louisiana.      TIM SLOAN/AFP via Getty Images

Source: NOLA.com

8. The Savannah Harbor Expansion Project ($158.9 million).

A truck picks up a shipping container at the Port of Savannah in Georgia.      Paul Hennessy/SOPA Images/LightRocket via Getty Images

Source: US Army Corp of Engineers and Georgia Ports Authority

9. Seattle Harbor Navigation Improvement Project ($61.2 million)

Kayakers pass Seattle's container port.      Wolfgang Kaehler/LightRocket via Getty Images

Source: American Association of Port Authorities

10. Baltimore Harbor and Channels Project ($33 million).

Baltimore, Maryland      Jose Luis Stephens/Shutterstock

Source: The Journal of Commerce