Pecans are as all-American as anything can be. Washington and Jefferson grew them. They are the state nut of Arkansas, Alabama and Texas. The U.S. grows about two-thirds of the world's pecans and chews most of them itself.

For generations, pecan prices have fallen with bumper crops and soared with lousy ones. But lately, they've only been going up. A pound of pecans in the shell fetched $2.14 on average last year, according to the U.S Department of Agriculture, nearly double what they brought three years earlier.

The reason: The Chinese want our nuts.

Five years ago, China bought hardly any pecans. In 2009, China bought one-quarter of the U.S. crop, and there's no sign demand is abating.

At a Carrefour store near Beijing's Sanyuan Bridge, Liu Wei, a 61-year-old retired chemistry teacher, is buying a 260-gram (9.1-ounce) bag of Orchard Farmer U.S.-grown pecans for 38 yuan ($5.78). That's nearly six times Beijing's official minimum hourly wage. "We used to eat only walnuts, and then we saw on TV that pecans are more nutritious than walnuts," she says.