Professor Rogers conducted research in three principal areas: immigration and the regional geography of the foreign-born population in the United States, elderly migration and settlement patterns, and the indirect estimation of migration. Imagine the geography of the foreign-born population in the United States at the middle of this century, and imagine its changes since then. How did the demographic processes of immigration, emigration, internal migration, and mortality act to shape the changing geography? How did the fertility patterns of foreign-borns and native-borns combine with the migration and mortality patterns of the latter to shape the geography of the native-born population and the consequent foreign-born shares of regional populations? How have the internal migration patterns of the foreign-borns differed from those of the native-born population? How have the internal migration patterns of the elderly differed from those of the non-elderly populations? Assisted by several graduate and undergraduate students, Professor Rogers has been seeking answers to such questions by modeling the spatial population dynamics of sub-populations in the United States during the past half-century.