U.S. airlines are increasingly looking to Asia to bolster their fortunes.

They’re forging alliances with Asian airlines, increasing flights to major cities and competing to launch service in fast-growing markets in the region.

The moves come as the Asia-Pacific region has edged past North America to be the largest aviation market in the world. In 2009, 647 million passengers flew within Asia-Pacific — which includes Asia, South Asia, Australia and New Zealand— compared with 638 million in North America, according to the International Air Transport Association.

“There’s no looking back,” says Derek Sadubin, chief operating officer for the Centre for Asia Pacific Aviation. “Asia’s leadership role in the global aviation scene won’t be challenged again.”

By 2013, 868 million travelers are expected to fly within Asia-Pacific, compared with 734 million in North America. China, one of the world’s fastest-growing economies, will lead the boom, analysts say, as its economy is expected to expand by nearly 10% annually for the next few years. To accommodate this growth, airlines will buy nearly 9,000 new aircraft for service in the Asia-Pacific market over the next 20 years, U.S. planemaker Boeing estimates. “Asia has a lot of people, and recently, the economy in places like China has grown very rapidly,” says Mark Kiefer, a principal in the aerospace division of Charles River Associates. “Where you have people with (rising) income, they’re disproportionately likely to travel.”