Growing trade between the United States and Asia has put strains on West Coast U.S. ports, especially the joint port of Los Angeles and Long Beach. Business leaders say the nation's largest port could use an upgrade.

It is a massive complex administered at one end by the city of Los Angeles and at the other by the city of Long Beach. Each section itself would qualify as the largest U.S. port, surpassing New York's.

For many years, the dual Los Angeles-Long Beach port has ranked as the world's third-busiest in shipping containers handled, after Hong Kong and Singapore. Now, says economist Jack Kyser, the complex ranks fourth or fifth, after the growing ports of Shanghai and possibly Shenzhen, China.

"We know that Shanghai has pushed ahead of Los Angeles-Long Beach, and then we understand there may be another port," said Jack Kyser. "But it just shows the boom in international trade that is going on. And of course, Los Angeles-Long Beach is the focal point for a lot of imports into the United States."

Mr. Kyser, who is chief economist with the Los Angeles County Economic Development Corporation, says the port needs to expand its capacity, without adding to the pollution of the local environment. He says new technology is helping, and so is a program that allows the moving of cargo nights and weekends.

"You have to improve productivity, and they are trying to do that," he said. "But what we are concerned about is landside infrastructure, which is the highways and the rail."

He says roads and rail lines need to be improved to keep the cargo flowing from the port to other parts of the country.

Chris Martin, chairman of the Los Angeles Chamber of Commerce, says the city has met more difficult challenges before. He notes the port has changed dramatically since 1836, when the writer Richard Henry Dana saw it, and later described it in Two Years Before the Mast, an account of his life as a seaman.

"A little wooden boat pulled up along the California coast," Mr. Martin said. "There was no harbor. They had to drop their anchor three miles out [about five kilometers] and have crews stand by to watch the ship in case the Sou'wester [wind] would blow in and blow them onto the rocks."

In 2004, ships also waited offshore, the sailors no longer fearing southwestern gales, but facing congestion at the port. Manufacturer Charlie Woo of the company Megatoys makes merchandise in China and distributes it in North America. He says the typical transit time from Asia to Los Angeles is about two weeks, and delays of several days, such as those he faced last year, can be disastrous.

"Nowadays, retail stores demand just-in-time delivery," Mr. Woo said. "So they do not want to store the merchandise ahead of time because they want to turn their space into shelf space. They do not want to have a large back room for merchandise. So they want their merchandise to arrive just in time so they can put it on the shelf for the season."

He says this is a slow time of the year at the Los Angeles-Long Beach port. He worries, however, about possible delays when the busy season starts in August and September, as merchandise arrives in advance of the Christmas season.