Even with a 400-year history of attracting immigrants from around the world, the United States continues to prefer newcomers with white faces, says UC Davis immigration historian Bill Ong Hing.

In his new book "Defining America Through Immigration Policy," Hing explores links between traditional racial concepts of who is a true American and how we enforce federal immigration policies.

"Immigration policies are not simply reflections of whom we regard as potential Americans, they are vehicles for keeping out those who do not fit the image and welcoming those who do," says Hing, a professor of law and Asian American studies.

In his book, Hing shows how immigration policies excluded the "undesirable Asians" in the 19th century. He also covers the 1917 literacy law; the 1952 act that excluded communists, homosexuals and other undesirables; discriminatory quotas; and diversity visas.

He also explores why Americans condone policies that push Mexican migrants to travel north through remote, uninhabited deserts, placing them in mortal danger.

"The American public has come to devalue the lives of undocumented Mexican border-crossers, having been conditioned to view these people as something other than potential Americans," Hing says.

The events of Sept. 11 reminded Americans that the United States is a nation of immigrants that has grown increasingly diverse since 1965, Hing says. However, the acts of terrorism also triggered broad government targeting of racial and ethnic groups.

"Our nation's immigration and refugee policies tell us much about ourselves, including whom we tolerate, much less respect," Hing says.