Chinese tourists visit a shopping center in Costa Mesa, California. Pic: AP.

COSTA MESA, California (AP) — Tourism from China to the U.S. has soared since the countries signed an agreement in 2007 promoting travel.

More than 1.8 million Chinese visited last year, a three-fold increase in five years. By 2018, the number of Chinese visitors is expected to surpass 4 million, according to the U.S. Department of Commerce.

California is the No. 1 destination. Popular tourist destinations have translated maps and brochures to Mandarin to cater to the tourists, and some hotels are serving congee, or rice porridge, for breakfast and providing in-room tea service.

There’s good reason to make the Chinese feel at home: They each spend an average of $5,400 during their travels, 21 percent more than the average for all overseas tourists.