Below we provide detail on selected terms used on the Atlas and how people are categorized by race/ethnicity, nativity, and ancestry.

Broad racial/ethnic origin

In the Atlas, categorization of people by race/ethnicity is generally based on individual responses to various census surveys. Unless otherwise noted, people are categorized into six mutually exclusive groups based on their response to two separate questions on race and Hispanic origin as follows:

• “White” and “non-Hispanic White” are used to refer to all people who identify as White alone and do not identify as being of Hispanic origin.
• “Black” and “African American” are used to refer to all people who identify as Black or African American alone and do not identify as being of Hispanic origin.
• “Latino” is used to refer to all people who identify as being of Hispanic origin, regardless of racial identification.
• “Asian or Pacific Islander” and “API” are used to refer to all people who identify as Asian American, Native Hawaiian, or Pacific Islander alone and do not identify as being of Hispanic origin.
• “Native American” is used to refer to all people who identify as Native American or Alaskan Native alone and do not identify as being of Hispanic origin.
• Other” or “Mixed/other” are used to refer to all people who identify with a single racial category not included above, or who identify with multiple racial categories, and do not identify as being of Hispanic origin. Importantly, prior to the 2000 Census the questionnaire did not allow for multiple responses to the race question, causing some degree of inconsistency in data for this racial/ethnic category before and after 2000.
• “People of color” is used to refer to all people who do not identify as non-Hispanic White.

Ancestry

In the Atlas, some indicators based on the IPUMS microdata provide data for people grouped by ancestry, with both broad and detailed ancestral groups identified. The purpose of the data by ancestry is to provide further information on equity indicators and population diversity for distinct subgroups within each of the mutually exclusive broad racial/ethnic groups described above (except for the Mixed/other group; we did not disaggregate the Mixed/other racial/ethnic group by ancestry mainly because, for this population, a more appropriate/interesting disaggregation would be by the various racial/ethnic groups people identify with rather than by ancestry—and that would be inconsistent with the way we disaggregate the other five major racial/ethnic groups). For this reason, the ancestral groupings were defined based on examining each broad racial/ethnic group separately, and selecting the ancestries within each group that captured a reasonably large number of people identified nationwide. Therefore, some ancestral groups are included in more than one broad racial/ethnic group. For example, data for those of Panamanian ancestry is broken out and reported on for both the Black and Latino populations, while data for those of Irish ancestry is available for both the Black and White populations (subject to sample size limitations in the IPUMS data).

The ancestral groups broken out for each broad racial/ethnic group other than Native Americans are based on the first response to the census question on ancestry, recorded in the IPUMS variable “ANCESTR1.” For Native Americans, they are based on the detailed responses to the census question on race, recorded in the IPUMS variable “RACED.” The reason for this that the vast majority of responses for Native Americans to the ancestry question (about 75 percent in most years) are coded in the ANCESTR1 variable as simply “American Indian (all tribes)” while the responses reflected in the RACED variable identify a variety of detailed Native American tribes.

For each broad racial/ethnic group, the responses to ANCESTR1 (or RACED, for Native Americans) were examined and the most common responses were identified nationwide. These became the detailed ancestral groups reported in the Atlas, and tend to reflect specific countries or ethnicities (or tribes, for Native Americans). The detailed ancestral groups were then organized into broader groups based on geography. These broader ancestral groups are reported in the Atlas. They tend to reflect continents of the world (or U.S. regions, for Native Americans), and were defined to include, in addition to their constituent detailed ancestries, all other relevant detailed ancestries not listed on the Atlas. Finally, a residual “Other” broad ancestral category was defined for each race/ethnicity to include all people for which the response to the ancestry (or race) question was too ambiguous to assign to any of the broad ancestries identified. (For the Black population, this residual “Other” broad category is mostly comprised of people who identified as being of “African-American” or “Afro-American” ancestry, and thus the category is labelled “African American/Other Black.”) Thus, while the detailed ancestral groups only account for a portion of each racial/ethnic population, the broad ancestral groups (including the residual “Other” broad ancestral category that appears for each race/ethnicity) account for the entire racial/ethnic population. Finally, in an effort to strike some balance between the numbers of detailed ancestries reported within each broad ancestral group, only the eight detailed ancestral groups with the largest populations in in the United States were broken out within each broad group.

As an example of how this classification scheme works, consider the Asian or Pacific Islander population. Within this broad racial/ethnic group, Vietnamese is a detailed ancestral group within the broader Southeast Asian ancestral group. The Southeast Asian ancestral group also includes those of Malaysian ancestry, even though they are not included among the detailed groups that are broken out.

Both detailed and broad sets of ancestral groups were created within each broad race/ethnicity so we could maximize the amount of racial/ethnic subgroup data reported in the Atlas. For example, because we do not report data for Atlas indicators and geographies that are based upon a small underlying sample size (see “A note on sample size,” below), many regions would have very little or no data by ancestry reported on the Atlas if we were to only designate the detailed ancestral groups. Our strategy to break out both broad and detailed ancestral groups means that Atlas indicator data for the broader ancestral groups can often still be reported for geographies where the detailed ancestral group populations are not large enough to report on; in geographies with large and diverse populations, both broad and detailed data are likely to be reported.

While most of the broader geographic groupings should be intuitive and are largely based on the IPUMS documentation for the ANCESTR1 variable, the way we defined those for Native Americans, and for the Middle East/North African group that is broken out for the White population, deserve a bit of explanation. Due to the lack of a generally accepted geographic categorization of Native American tribes in the United States, we relied upon a variety of maps of Native American regions found on the internet and applied what appeared to be the most common broad geographic groupings (e.g., Northwest Coast, Great Plains, Eastern Woodlands) into which the detailed Native American ancestries were assigned. The latter assignment was guided by maps of Native American tribes in the continental United States created by Aaron Carapella, among other online sources.5 To define the Middle East/North African broad ancestral group that is broken out for the White population, we included all ancestries classified under “North African and Southwest Asia” in the IPUMS documentation for the ANCESTR1 variable.

Nativity

The term “U.S.-born” refers to all people who identify as being born in the United States (including U.S. territories and outlying areas), or born abroad of at least one U.S. citizen parent. The term “immigrant” refers to all people who identify as being born abroad, outside of the United States, of non-U.S. citizen parents.

Other selected terms

Below we provide definitions and clarification around some of the terms used in the Atlas.

• The term “communities of color” generally refers to distinct groups defined by race/ethnicity among people of color.
• The term “full-time” workers refers to all persons who reported working at least 45 or 50 weeks (depending on the year of the data) and usually worked at least 35 hours per week during the year prior to the survey. A change in the “weeks worked” question in the 2008 American Community Survey (ACS) caused a dramatic rise in the share of respondents indicating that they worked at least 50 weeks during the year prior to the survey, as compared with prior years of the ACS and the long form of the decennial census. To make our data on full-time workers more comparable over time, we applied a slightly different definition in 2008 and later than in earlier years: in 2008 and later, the cutoff applied to identify full-time workers is at least 50 weeks while in 2007 and earlier it is 45 weeks per year. The 45-week cutoff was found to produce a national trend in the incidence of full-time work over the 2005–2010 period that was most consistent with that found using data from the March Supplement of the Current Population Survey, which did not experience a change to the relevant survey questions. For more information, see https://www.census.gov/content/dam/Census/library/working-papers/2007/acs/2007_Holder_02.pdf.
• The terms “region,” “metropolitan area,” “metro area,” and “metro” all refer to the geographic areas defined as metropolitan statistical areas by the OMB under the December 2003 definitions.
• The term “housing unit” refers to the underlying physical sampling unit for the Decennial Census and the ACS. There are three types of housing units: households, group quarters, and vacant units.
• The term “group quarters” refers to residences that are institutions or other group-living arrangements that are owned or managed by an entity or organization providing housing and/or services for the residents.
• The term “household” refers to residences that are not group quarters.
• The term “civilian noninstitutional” refers to all persons who do not report employment in the armed forces and do not report living in an institution.
• The term “wage and salary workers” refers to all persons who report working during the year prior to the survey and report receiving wage and salary income but no self-employment income (e.g., income from a business, professional practice, or farm).
• The term “earned income” refers to all pre-tax wage and salary income received by employees.