With a few exceptions, data on the foreign-born population by country of birth refer to foreign countries as defined at each census. Thus, for example, data for Austria and Hungary to 1910 are not comparable to data for 1920 forward because of changes in the map of Europe following World War I. Even though Poland ceased to exist as an independent country in 1795, Poland was identified as a country of birth in U.S. censuses from 1850 to 1900. Poland was not so identified in 1910, but was again in 1920 following World War I. The 1910 foreign-born population with Polish mother tongue provides an estimate of the 1910 foreign-born population from Poland. The world regions of birth used here to classify the foreign-born population are Europe, Northern America (about 99 percent of which was from Canada in 2000), Latin America, Asia, Africa, and Oceania. For more information on time-series data on the foreign-born population by country of birth and world region of birth, see Campbell Gibson and Kay Jung (2006), “Historical Census Statistics on the Foreign-Born Population of the United States: 1850 to 2000,” U.S. Census Bureau, Population Division Working Paper No. 81.
Census reports for 1910 to 1930 showed data on the foreign-born White population for country of birth by mother tongue and for mother tongue by country of birth. These data shown in Figures 13-6 and 13-7 for 1910 and 1930, respectively. For many countries the data are not comparable for the two years due to boundary changes after World War I. In some cases, the countries and mother tongues of the foreign-born White population identify nearly the same population (e.g., Italy and Italian, or Norway and Norwegian). In other cases, there are major differences. For example, in 1910, the White foreign-born population from Austria was very diverse by mother tongue, with five different mother tongues each accounting for 10 percent or more of the total.