own identification as they had since the 1970 census. (Such self-identification has been used in censuses since 1970, though with different categories; before that, interviewers classified respondents.)
Self-identification sometimes gives people options, depending on the context. Racial and ethnic identities vary as a function of social and psychological factors that may alter their salience (Yancey et al., 1976). For instance, with the decline of stigma and greater emphasis on the rights of indigenous peoples, the number of people who say they are American Indians or Alaska Natives has increased over time far faster than would be possible from natural increase (Harris and Sim, 2002). A questionnaire provides sample categories that also can affect individuals’ choices. English was the largest ethnic group in the 1980 U.S. census, but the size of this group declined by 34 percent when it was not listed as an example in 1990 (Waters, 2000:1730).
As self-identification has become the norm, pressure has grown to allow multiple and interracial identification, which was done in the 2000 census. When asked to choose one race, more than 80 percent of multiracial individuals will do so (Sondik et al., 2000), but given the option of multiple identities, some people choose more than one, with more educated people being more likely to do so (Lieberson and Waters, 1993). Again, this depends on context. For instance, adolescents choose multiracial identities on surveys more often at school than at home (Harris and Sim, 2002). In the 2000 census, 2.4 percent of the population chose more than one race (U.S. Census Bureau, 2002b).
The categories used by the U.S. Office of Management and Budget (OMB) are a small part of the possible racial and ethnic distinctions that might be made among Americans. An encyclopedia of immigrant groups (Levinson and Ember, 1997) provides profiles of 161 groups, from Acadians to Zoroastrians, and this does not include native groups, such as the more than 550 American Indian tribal groups recognized by the Bureau of Indian Affairs. There are of course almost an infinite number of physical and cultural characteristics that could be used to define racial and ethnic groups, and the major groups are defined with reference to a very small subset of these.
In this report we generally follow the OMB classification, with minor modifications (at least partly to accommodate earlier data and studies). We treat Hispanics as a distinct group and all other groups referred to in this report explicitly exclude Hispanics. We do not distinguish Native Hawaiians and Pacific Islanders, treating them together with Asians when the data require this or leaving them out. We treat American Indians and Alaska Natives as a single group. We do not identify Alaska Natives separately since they account for only 0.03 percent of the combined group and are not distinguished (and are probably not represented) in any of the studies we