While Panamanians take great pride in their canal and their success in running the waterway since the United States returned the canal to Panama in 1999, there’s still plenty at stake for the United States with the expansion.

Two-thirds of the goods that move to and from the United States cross the Panama Canal, and the United States is the canal’s leading customer.

Wal-Mart, Lowe’s, Home Depot and Target are clamoring to import products from Asia not only more quickly but also more cheaply.

“Time is money,’’ said U.S. Trade Representative Ron Kirk. The expansion of the canal “can have an explosive impact on our ability to move goods from the United States to other parts of the world — and for areas that are uniquely situated like Florida, it could be a huge benefit.’’

Understanding

the size and scope

If construction of the original Panama Canal, which was completed in 1914, was the moonshot of its era, the current canal project also is something of an engineering marvel.

Some 4.2 million cubic meters of concrete — about 40 percent more than for the original canal — will be poured by the time the new three-chambered locks are completed. Each 180-foot-wide, 1,400-foot-long chamber could accommodate the Empire State Building laid on its side. The gates for the locks, which are being built in Italy, will soar 10 stories high.

The canal’s new set of locks will allow a ship with a 160-foot beam to pass with ease. The current canal can accommodate only ships that are no more than 106 feet wide and 965 feet long with a draft — or depth — of 39 1/2 feet, instead of the 50 feet or so required by post-Panamax vessels. Some of the largest ships in this category — with containers stacked seven deep on their decks — look like they’re barely able to squeeze through today’s locks.

Most of these vessels carry around 5,000 standard 20-foot containers. But the post-Panamax behemoths can stretch the length of three football fields and will carry as many as 13,000 containers as they make the eight-to-10-hour journey through the canal. In terms of tonnage, they’re three times as heavy as current Panama Canal ships, hence the need for deeper channels and wider locks.

The canal expansion isn’t about moving more ships so much as accommodating bigger ones. Since 1965, the number of ships traversing the canal annually has remained at about 14,000, but the tonnage they transport has tripled.

“The business of the canal is to move cargo, not vessels. It’s basically how much tonnage can you move. The expansion makes the canal much more efficient,’’ said Alberto Alemán, the former chief executive of the Panama Canal Authority.

Quijano, who succeeded Alemán in September, works out of the same wing of a landmark building high on a hill above the canal’s Pacific entrance as U.S. canal administrators did for eight decades. But now only one flag — the Panamanian one — waves from atop the building, which features a domed rotunda adorned with murals of canal construction.

During a recent interview, Quijano apologized for his construction boots and work shirt but explained he had just returned from Colón where he was checking the progress on the new Atlantic locks.

But Quijano, a U.S.-trained engineer, is used to getting dirty. He served as project manager for the expansion until his promotion and has worked for the canal since 1975, when both the Canal Zone — a five-mile wide strip of land on either side of the canal — and the canal itself were still controlled by the United States.