If you ask most people living in America to name their ancestors' country of origin, they might select England or Norway or Mexico or maybe even a continent. Or they might list a combination of foreign places.

Unless you're an American Indian, your ancestors are likely from overseas.

Yet, for an estimated 183,522 Utahns, the reply is simply "American." It's the state's fourth most common ancestry, after English, German and Mexican, according to the U.S. Census' 2005 American Community Survey, which asks respondents to write in their ancestry or ethnic origin.

The number of people selecting American ancestry is growing. In 1990, 57,268 Utahns reported only American as their ancestry. The number grew to 150,814 by the 2000 Census.

Why people feel that way is difficult to determine, in part because of the anonymity of the census. A cross section of professionals including demographers, sociologists and genealogists came up with a variety of theories. It could be a simple misunderstanding of the question, or maybe people don't know their ancestry.

Or it might even be a post-Sept. 11 form of patriotism.

When the Census Bureau first asked the question in 1980, demographers weren't quite sure what to make of the "American" response, said Angela Brittingham, a U.S. Census Bureau demographer.

"The consensus was, it wasn't a real ancestry," Brittingham said. But the number of people who said their ancestors were "American" represented 5 percent of the nation's population in 1990 and grew to 7 percent in 2000.

The question is separate from others such as those that ask a person's citizenship, race or origin.

While there's space for more than one ancestry, in order to be counted as having "American" ancestry, a person must write in only American, she said. So, if someone writes Asian American, only the Asian will be counted. Those who write in U.S.A. or a state's name are included in the "American" category.

"It's pretty much accepted; we're now treating it as an ancestry," Brittingham said. "So many people are saying it. ... They're saying it because that's what they feel."

It could be that individuals, especially those with mixed ancestries, don't readily know the details of their ancestry, suggested Robert Spendlove, manager of demographic and economic analysis for the Governor's Office of Planning and Budget.

The average person spends, at the most, 30 seconds on a census question and isn't going to do research to answer it, he said.

"It's just human nature. You're going to do what's easiest," Spendlove said. "If I'm American and I lived in America all my life and parents lived in America all their lives, that's my response to this question."