NEW YORK - About 40 percent of white Americans and about 25 percent of non-white Americans are surrounded exclusively by friends of their own race, according to an ongoing Reuters/Ipsos poll.

The figures highlight how segregated the United States remains in the wake of a debate on race sparked by last month's acquittal of George Zimmerman in the shooting of unarmed black Florida teenager Trayvon Martin. President Barack Obama weighed in after the verdict, calling for Americans to do some "soul searching" on whether they harbor racial prejudice.

There are regions and groups where mixing with people of other races is more common, especially in the Hispanic community where only a tenth do not have friends of a different race. About half of Hispanics who have a spouse or partner are in a relationship with non-Hispanics, compared to one tenth of whites and blacks in relationships.

Looking at a broader circle of acquaintances to include coworkers as well as friends and relatives, 30 percent of Americans are not mixing with others of a different race, the poll showed.

Respondent Kevin Shaw, 49, has experienced both integration and racial homogeny. He grew up in downtown Kansas City, Missouri, and attended a mixed high school where he was one of only two white teenagers on the mostly black football team. His wife, Bobbi, is Hispanic. They met in high school and have been married for 27 years.

Eleven years ago, they moved to a predominantly white neighborhood in the suburb of Liberty. "Soon after we moved in, my mother-in-law came to visit and a neighbor asked if she was my maid. It was just a matter of ignorance," he said.

In the time he has lived there the neighborhood has become less blinkered, helped by the arrival of younger families.

He also puts prevailing attitudes down to environment. "A lot of it comes down to where you grow up," he said.