Nearly 400,000 people in Oregon were born in other countries.

The biggest source of foreign-born Oregonians, according to census data, is Mexico. There's a problem, though: Nearly all of the 150,000 Mexican-born Oregonians moved here more than a decade ago. Since 2009, research by the Oregon Office of Economic Analysis shows, only a couple of thousand people have made the trek north. Most of the state's population growth in the past few years has come in the form of non-Hispanic whites.

But there's good news for one of the most homogenous states in the nation: Immigration from Asia, particularly China, is booming.

"Where new residents differ the most is the higher share of Asian migrants—twice as large as the current population in percentage terms," says Josh Lehner, a state economist. "The breakdown among Asians is about 34 percent Chinese, 11 percent Japanese, and 55 percent all other Asian countries or Pacific islands."

Lehner says nobody is quite sure what's caused the shift in immigration flows.

Some of the increase is due to people coming from Asia for educational and economic opportunities. And the changes also reflect a reduction in traditional pathways.

"Some of it has to do with slowdowns in immigration from other places, meaning it has to come from Asia and Africa," Lehner says, "because we are no longer seeing European or Latin America migration in big numbers."