The ports of Los Angeles and Long Beach have long held the title for most containerized cargo passing through their terminals. But the two ports have another, lesser-known title these days: king (of) cotton.

Indeed, half of the nation’s 17 million bales of cotton exports now exit from the two ports, driven by the seemingly insatiable demand from Chinese textile mills and garment makers.

“China has really emerged in the last few years to be the biggest buyer of U.S. cotton, and to get that cotton to China, you need to ship out through the L.A.-area ports,” said Mark Bagby, director of communications for Calcot, a marketing cooperative of the major growers in California, Arizona and south Texas.

Steadily rising demand in China for cotton and other basic commodities like paper are the major reason why exports from the twin ports have grown by double digits in recent years and are on track to do so again this year.

Decades ago, most of the cotton grown in the U.S. was consumed domestically by huge textile mills in the eastern half of the country. But as the garment industry has gone offshore, so have the mills. And in the last several years, China has exploded on the scene; that country imported about 20 million bales of cotton last year.

In fact, China’s cotton growers have raised concerns that they will be put out of business because of the increase in the amount of cotton imports.

Cotton is one of the few commodities that can be containerized; about 85 refrigerator-sized bales can fit in a container. That makes it easy to transport the cotton to port.

Some of the cotton grown in the Eastern U.S. is transported via truck or train to ports on the Gulf Coast and ends up in major markets like Turkey. But most of the rest and virtually all of the cotton grown in California and Arizona goes to the Ports of Los Angeles and Long Beach.

In the 2004-05 growing season, a total of 14.4 million bales of cotton were exported from the U.S., up slightly from 13.4 million bales in 2003-04, Bagby said. And thanks to favorable growing conditions and the surging Chinese demand, exports have shot up to an estimated 17 million bales in the 2005-06 season.

Still, imports still swamp exports at the ports, with empty containers that once transported televisions, computers and other equipment to the U.S from Asia remaining a leading export.