Information on place of birth and citizenship status was used to classify the population into two major categories: native and foreign born. (See "Native" and "Foreign Born" under "Citizenship Status.")

The native population includes people born in the United States, Puerto Rico, or the U.S. Island Areas (such as Guam). People who were born in a foreign country but have at least one American (U.S. citizen) parent also are included in this category. The native population includes anyone who was a U.S. citizen at birth.

The foreign-born population includes all people who were not U.S. citizens at birth. Foreign-born people are those who indicated they were either a U.S. citizen by naturalization or they were not a citizen of the United States.

Census 2000 does not ask about immigration status. The population surveyed includes all people who indicated that the United States was their usual place of residence on the census date. The foreign-born population includes: immigrants (legal permanent residents), temporary migrants (e.g., students), humanitarian migrants (e.g., refugees), and unauthorized migrants (people illegally residing in the United States).

The foreign-born population is shown by selected area, country, or region of birth. The places of birth shown in data products were chosen based on the number of respondents who reported that area or country of birth. (See "Place of Birth.")

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.")