The data on ancestry were derived from answers to Question 12. The question was based on self-identification; the data on ancestry represent self-classification by people according to the ancestry group(s) with which they most closely identify. Ancestry refers to a person's ethnic origin or descent, "roots," or heritage; or the place of birth of the person, the person's parents, or ancestors before their arrival in the United States. Some ethnic identities, such as "Egyptian" or "Polish" can be traced to geographic areas outside the United States, while other ethnicities such as "Pennsylvania German" or "Cajun" evolved in the United States.
The intent of the ancestry question was not to measure the degree of attachment the respondent had to a particular ethnicity, but simply to establish that the respondent had a connection to and self-identified with a particular ethnic group. For example, a response of "Irish" might reflect total involvement in an Irish community or only a memory of ancestors several generations removed from the individual.
The Census Bureau coded the responses into a numeric representation of over 1,000 categories. To do so, responses initially were processed through an automated coding system; then, those that were not automatically assigned a code were coded by individuals trained in coding ancestry responses. The code list reflects the results of the Census Bureau's own research and consultations with many ethnic experts. Many decisions were made to determine the classification of responses. These decisions affected the grouping of the tabulated data. For example, the "Indonesian" category includes the responses of "Indonesian," "Celebesian," "Moluccan," and a number of other responses.
The ancestry question allowed respondents to report one or more ancestry groups. Generally, only the first two responses reported were coded. If a response was in terms of a dual ancestry, for example, "Irish English," the person was assigned two codes, in this case one for Irish and another for English. However, in certain cases, multiple responses such as "French Canadian," "Scotch-Irish," "Greek Cypriot," and "Black Dutch" were assigned a single code reflecting their status as unique groups. If a person reported one of these unique groups in addition to another group, for example, "Scotch-Irish English," resulting in three terms, that person received one code for the unique group (Scotch-Irish) and another one for the remaining group (English). If a person reported "English Irish French," only English and Irish were coded. For certain combinations of ancestries where the ancestry group is a part of another, such as "German Bavarian," the responses were coded as a single ancestry using the more detailed group (Bavarian). Also, responses such as "Polish-American" or "Italian-American" were coded and tabulated as a single entry (Polish or Italian).
The Census Bureau accepted "American" as a unique ethnicity if it was given alone, with an ambiguous response, or with state names. If the respondent listed any other ethnic identity such as "Italian American," generally the "American" portion of the response was not coded. However, distinct groups such as "American Indian," "Mexican American," and "African American" were coded and identified separately because they represented groups who may consider themselves different from those who reported as "Indian," "Mexican," or "African," respectively.
In all tabulations, when respondents provided an unclassifiable ethnic identity (for example, "multi-national," "adopted," or "I have no idea"), the answer was included in "Unclassified or not reported."
The tabulations on ancestry use two types of data presentations - one used total people as the base, and the other used total responses as the base. The following are categories shown in the two data presentations.
Presentations Based on People
People Reporting Single Ancestry
Includes all people who reported only one ethnic group such as "German." Also included in this category are people with multiple-term responses such as "Scotch-Irish" who are assigned a single code because they represent one distinct group.
People Reporting Multiple Ancestries
Includes all people who reported more than one group, such as "German" and "Irish" and were assigned two ancestry codes.
People Reporting Ancestry
Includes all people who reported each ancestry, regardless of whether it was their first or second ancestry, or part of a single or multiple response.
Presentations Based on Responses
Includes the first response of all people who reported at least one codeable entry. For example, in this category, the count for Danish would include all those who reported only Danish and those who reported Danish first and then some other group.
Includes the second response of all people who reported a multiple ancestry. Thus, the count for Danish in this category includes all people who reported Danish as the second response, regardless of the first response provided.
Total Ancestries Reported
Includes the total number of ancestries reported and coded. If a person reported a multiple ancestry such as "French Danish," that response was counted twice in the tabulations--once in the French category and again in the Danish category. Thus, the sum of the counts in this type of presentation is not the total population but the total of all responses.
Although some experts consider religious affiliation a component of ethnic identity, the ancestry question was not designed to collect any information concerning religion. The Census Bureau is prohibited from collecting information on religion. Thus, if a religion was given as an answer to the ancestry question, it was coded as an "Other" response.
Beginning in 2006, the population in group quarters (GQ) is included in the ACS. Some types of GQ populations may have ancestry distributions that are different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the ancestry distribution. This is particularly true for areas with a substantial GQ population.
The 1996-1999 American Community Survey system for coding required consistency checks with answers to other questions when the write-in response to ancestry was "Indian." The coding in 2000 and subsequent years involved consistency checks for those respondents writing "Indian" and for two-word ancestries containing the word "Black," such as "Black Irish." Since 1999, the list of examples differed from those used for the 1996-1998 ACS.