What does ancestry mean? The Census Bureau defines the term ancestry:
Ancestry refers to a person's ethnic origin or descent, "roots," or heritage, or the place of birth of the person or the person's parents or ancestors before their arrival in the United States. Some ethnic identities, such as "German" or "Jamaican" can be traced to geographic areas outside the United States, while other ethnicities such as "Pennsylvania Dutch" or "Cajun" evolved in the United States.
The intent of the ancestry question is not to measure the degree of attachment the respondent had to a particular ethnicity. 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. A person's ancestry is not necessarily the same as his or her place of birth, i.e., not all people of German ancestry were born in Germany (in fact, most weren't).
Source: U.S. Census Bureau, Population Division, Ethnic & Hispanic Statistics Branch
In these modern times, the question about ancestry is asked on both the 2000 Census and the American Community Survey (ACS).
The ancestry question is asked "What is your ancestry or ethnic origin?" The question also provides examples of particular ethnic groups, which have changed since 1980. The response options to the question are two blank spaces in which respondents can write in whatever ancestry or ancestries they want.
In 1980 the question was "What is your ancestry?", which is slightly different than in 1990 and 2000 in that it didn't include the term "ethnic origin".