The U.S. population total and population change have been adjusted to be consistent with the results of the 2020 Census. The components of population change have not been adjusted and so inconsistencies will exist between population values derived directly from the components and the population displayed in the odometer and the Select a Date tool.
The U.S. population clock is based on a series of short-term projections for the resident population of the United States. 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, 2010 resident population from the 2010 Census.
At the end of each year, a new series of population estimates, from the census date forward, is used to revise the 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.