The Port of Seattle is considering a US$200 million modernisation programme that would see its Terminal 5 able to dock more mega-ships.
The port recently released a draft environmental impact statement for the plan.
The modifications include berth deepening, dock strengthening, and power upgrades to handle larger cranes.
John Creighton, president of the Port of Seattle Commission, said modernising Terminal 5 was vital to cater for the trend to fewer but larger vessels.