Demographic Change in the United States, 1970 – 2050

Population projections demonstrate the implications of sets of fertility, mortality, and migration rates, combined with an initial population age structure, for future population size and composition. Age-specific mortality rates are applied to project the living population forward in time; age-specific fertility rates are applied to project births. Immigrants and emigrants are typically added at the last stage. Projections make endogenous one of the most important determinants of demographic change, a population’s age structure. Populations with larger proportions over age 50, for example, have higher death rates and lower birth rates and growth rates, ceteris paribus.