The Population Estimates Program publishes total resident population estimates and demographic components of change (births, deaths, and migration) each year. We also publish the estimates by demographic characteristics (age, sex, race, and Hispanic origin) for the nation, states, and counties. In addition to the resident population universe, we also produce population estimates for these universes: resident plus armed forces overseas, civilian, and civilian noninstitutionalized at the national level; and civilian at the state level. The reference date for estimates is July 1.
Projections are estimates of the population for future dates. They illustrate plausible courses of future population change based on assumptions about future births, deaths, net international migration, and domestic migration. Projected numbers are typically based on an estimated population consistent with the most recent decennial census as enumerated, projected forward using a variant of the cohort-component method.
In some cases, several alternative series of projections are produced based on alternative assumptions for future fertility, life expectancy, net international migration, and (for state-level projections) state-to-state or domestic migration. For each of these components of population change--fertility, mortality and net migration--three different assumptions about the future are applied. The series using the middle assumption for each component--generally designated as the "middle series"--is the most commonly used. Population projections are produced by age, sex, race and Hispanic origin, and are released periodically.