Population Estimates
Contents
The Population Estimates Program (PEP) is a U.S. Census Bureau program that produces annual population estimates for the years between each decennial census. These estimates cover the United States, states, counties, metropolitan and micropolitan statistical areas, and other local governmental units. The program also provides estimates for demographic components of change, like births, deaths, and migration. The estimates are used to allocate federal funding, as controls for other surveys like the American Community Survey (ACS), and as indicators of recent demographic shifts.
Methodology and Data Sources
The PEP's methodology, sometimes referred to as the Cohort-Component Method, starts with the most recent decennial census as a base. It then updates the population count by adding births, subtracting deaths, and accounting for net migration (both domestic and international) for each year.
The program relies on a variety of data sources to calculate these demographic changes:
| • | Vital Statistics: Data on births and deaths are sourced from the National Center for Health Statistics (NCHS). |
| • | Migration Data: Estimates for net domestic migration are based on data from the Internal Revenue Service (IRS), while net international migration estimates use a combination of data from the ACS, NCHS, and the previous census. The movement of the military is tracked using data from the Defense Manpower Data Center. |
| • | Housing Data: The program also uses the Housing Unit Method, which relies on building permit data, to help distribute population estimates to smaller geographic areas like cities and towns. |
Decennial Census vs. Population Estimates Program
While both the decennial census and the PEP are conducted by the Census Bureau, they serve different purposes and have key differences:
| • | Frequency: The decennial census is a count of the U.S. population conducted every 10 years to fulfill the constitutional requirement of congressional apportionment. The PEP produces population estimates annually during the years between each decennial census. |
| • | Purpose: The census is a complete count of the entire population, providing an official baseline. In contrast, the PEP provides a continuous, updated series of population estimates that reflect changes since the last census. |
| • | Methodology: The decennial census is a survey that aims to count every person and housing unit. The PEP uses a "blended base" approach that integrates the most recent census data with administrative records and statistical models to create its estimates. |