A question on place of birth has been included in the decennial census since 1850. Information collected on this item has been used to identify the state in the United States or outlying area of the United States (e.g., Puerto Rico) or foreign country in which each individual was born. Data on the native and foreign-born population are generally consistent over time, although the definition of the native population has been refined. Since 1890, the individuals who were born in a foreign country, but who had at least one parent who was a U.S. citizen, have been defined as native rather than as foreign born. Since 1890, the native population has been defined to include all individuals who were born in the United States, born in an outlying area of the United States, or born in a foreign country with one or both parents U.S. citizens. The native population is thus the population with U.S. citizenship at birth, regardless of place of birth.
For the native population born in the United States, information on state of residence and state of birth together provides a rough measure of lifetime migration among states which can be cumulated to show interregional migration. The information does not specify when the migration occurred or anything about intermediate moves, but it does provide a general indication of lifetime migration over the preceding generation or two for the enumerated population. One weakness in these data is due to the increasing proportion of births occurring in hospitals in the 20th century because a person’s state of birth may differ from his or her original state of residence. For example, in Figure 11-5, some of the 490,000 persons born in Washington, DC and living in Maryland in 2000 were born to mothers living in Maryland suburbs in the Washington, DC metropolitan area. The interpretation of trends in net lifetime interregional migration can be illustrated with reference to Figure 11-3. With no interregional migration after a certain date, the net figure will eventually become zero with the attrition by death of persons who migrated. An increase in a net in-migration (e.g., in the West until 1980) indicates continued net immigration to the region in each decade. Similarly, a net out-migration that becomes more negative (e.g., the North from 1930 to 2010) indicates continued net out-migration each decade. The data indicate a major change for the South from 1960 to 2010, from a sizable net out-migration to a sizable net inmigration.