The foreign stock is classified by country of origin--either country of birth or country of birth of parents. Separate distributions are shown for the foreign born (based on country of birth) and for the native population of foreign or mixed parentage (based on country of birth of parents). Native persons of foreign parentage whose parents were born in different foreign countries are classified according to the fathers country of birth.

Countries specified in the distributions comprise those officially recognized by the U.S. State Department at the time of the census. (Respondents were asked to report country of birth according to international boundaries recognized by the U.S. at the time of enumeration and to distinguish between Ireland and Northern Ireland. ) Over 80 countries are separately shown in some country of origin tabulations.