U.S. Census Bureau

U.S. PopClock Projections of the Resident Population
of the United States, as of 12:01 A.M. Each Day


Technical Description

The Population Clock shows a series of near-term projections for the United States resident population. This includes people whose usual residence is in the 50 States and the District of Columbia. These projections do not include members of the Armed Forces overseas, their dependents, or other U.S. citizens residing outside the United States. The projections are based on a monthly series of population estimates starting with the April 1, 2000 resident population from Census 2000.

The April 1 population count is updated by adding births, subtracting deaths, and adding net migration (international migration, as well as the movement of Armed Forces and other U.S. citizens between the United States and abroad) that occurred in the United States since the Census date. These components of population change are estimates based on data obtained either monthly or yearly from various Federal agencies. At the end of each year, a new series of population estimates, from the census date forward, is used to revise any or all postcensal estimates, including the population clock projections series. Once a series of monthly projections is completed, the daily population clock numbers are derived by interpolation. Within each calendar month, the daily numerical population change is assumed to be constant, subject to negligible differences caused by rounding.

Population estimates produced by the U.S. Census Bureau for the United States, states, or substate areas can be found on the Population Estimates web page, while long-term projections for the United States and states can be found on the Population Projections web page.