The federal government is required to take a census (a count) of the population every 10 years. The U.S. Census Bureau updates the decennial census with estimates of the population each year.

The Population Estimates Program publishes total resident population estimates and demographic components of change (births, deaths, and migration) each year. This program also publishes the estimates by demographic characteristics (age, sex, race, and Hispanic origin) for the nation, states and counties. The reference date for estimates is July 1. With each new issue of July 1 estimates, estimates are revised for years back to the last census. Previously published estimates are superseded and archived.

Source: U.S. Census Bureau

Frequently Asked Questions

• What is the difference between a count, an estimate and a projection?
  A count is what happens during the decennial census when residents are literally "counted." Estimates are prepared each year between censuses to capture changes in an area. Projections are forecasts of the population into the future.