The data on place of birth were derived from answers to long-form questionnaire Item 12 which was asked of a sample of the population. Respondents were asked to report the U.S. state, Puerto Rico, U.S. Island Area, or foreign country where they were born. People not reporting a place of birth were assigned the state or country of birth of another family member or their residence 5 years earlier, or were imputed the response of another person with similar characteristics. People born outside the United States were asked to report their place of birth according to current international boundaries. Since numerous changes in boundaries of foreign countries have occurred in the last century, some people may have reported their place of birth in terms of boundaries that existed at the time of their birth or emigration, or in accordance with their own national preference.

The place of birth question for residents of Puerto Rico was identical to the question on the stateside questionnaires. The same code lists were used to code the responses and similar edits were applied.

The data on citizenship were derived from answers to long-form questionnaire Item 13, which was asked of a sample of the population. On the stateside questionnaire, respondents were asked to select one of five categories: (1) born in the United States, (2) born in Puerto Rico or a U.S. Island Area (such as Guam), (3) born abroad of American parent(s), (4) naturalized citizen, (5) not a citizen. On the Puerto Rico questionnaire, respondents were asked to select one of five categories: (1) born in Puerto Rico, (2) born in a U.S. state, District of Columbia, Guam, the U.S. Virgin Islands, or the Northern Mariana Islands, (3) born abroad of American parent or parent(s), (4) U.S. citizen by naturalization, (5) not a citizen of the United States. People not reporting citizenship were assigned citizenship based on a set of criteria including the citizenship status of other household members and place of birth. (See "Place of Birth.")

A person having origins in any of the original peoples of Europe, the Middle East, or North Africa. It includes people who indicate their race as "White" or report entries such as Irish, German, Italian, Lebanese, Near Easterner, Arab, or Polish.

The data on the Hispanic or Latino population, which was asked of all people, were derived from answers to long-form questionnaire Item 5, and short-form questionnaire Item 7. The terms "Spanish," "Hispanic origin," and "Latino" are used interchangeably. Some respondents identify with all three terms, while others may identify with only one of these three specific terms. Hispanics or Latinos who identify with the terms "Spanish," "Hispanic," or "Latino" are those who classify themselves in one of the specific Hispanic or Latino categories listed on the questionnaire - "Mexican," "Puerto Rican," or "Cuban" - as well as those who indicate that they are "other Spanish, Hispanic, or Latino." People who do not identify with one of the specific origins listed on the questionnaire but indicate that they are "other Spanish, Hispanic, or Latino" are those whose origins are from Spain, the Spanish-speaking countries of Central or South America, the Dominican Republic, or people identifying themselves generally as Spanish, Spanish-American, Hispanic, Hispano, Latino, and so on. All write-in responses to the "other Spanish/Hispanic/Latino" category were coded.

Origin can be viewed as the heritage, nationality group, lineage, or country of birth of the person or the person's parents or ancestors before their arrival in the United States. People who identify their origin as Spanish, Hispanic, or Latino may be of any race.

Some tabulations are shown by the origin of the householder. In all cases where the origin of households, families, or occupied housing units is classified as Spanish, Hispanic, or Latino, the origin of the householder is used. (For more information, see the discussion of householder under "Household Type and Relationship.")

If an individual could not provide a Hispanic origin response, their origin was assigned using specific rules of precedence of household relationship. For example, if origin was missing for a natural-born daughter in the household, then either the origin of the householder, another natural-born child, or the spouse of the householder was assigned. If Hispanic origin was not reported for anyone in the household, the origin of a householder in a previously processed household with the same race was assigned. This procedure is a variation of the general imputation procedures described in "Accuracy of the Data," and is similar to those used in 1990, except that for Census 2000, race and Spanish surnames were used to assist in assigning an origin. (For more information, see the "Comparability" section below.)