Two US airline companies, Delta Air Lines Inc and United Airlines, have won two coveted new air routes to Shanghai and Guangzhou, and four other new routes have been proposed for 2009, US Secretary of Transportation Mary Peters said Tuesday.

The announcement was part of an agreement signed in July with China to double the number of daily flights between the US and China over the next five years. The agreement also allows for new cargo flights operating to and from the two nations.

Atlanta-based Delta will fly a route from Atlanta to Shanghai available in April, said Peters. Delta's flight to China's financial hotspot is the first to China by a US airline from the Southeast.

Chicago-based United will fly a route between Guangzhou - China's manufacturing center - and San Francisco starting in 2008 because of the US city's longtime "personal, cultural and business ties to China," Peters said.

Peters said the new routes "are the best way to break down barriers and misconceptions that too often come between our two countries." She predicted the increased air links between the two countries will improve relations and lower fares.

The transportation secretary also said other US-China routes have been proposed for 2009. They include New York to Shanghai for Continental Airlines and Detroit to Shanghai for Northwest Airlines. They also include Chicago to Beijing for American Airlines and Philadelphia to Beijing for US Airways. Those routes are under a public comment period and Peters said she hopes to make a decision in the near future.

Before Tuesday's announcement, four US carriers - American, Continental, Northwest and United - had a total of 10 daily passenger flights to Beijing, Guangzhou and Shanghai.

Delta CEO Richard Anderson said Peters' announcement was a "watershed event in terms of opening the Southeast United States to the Chinese marketplace."

He said the company expects to start daily flights by the end of March, provided the two new Boeing 777 aircraft it purchased for the route will be available from the manufacturer on time.