The decennial census is a complete count of the resident population as of April 1 of each census year. It is often used for legal purposes such as redistricting. 

Intercensal estimates are revised estimates for each year between two decennial census counts. They are the most accurate estimates for non-census years but are only available for a previous decade after the most recent decennial census. Estimates are available for incorporated places, counties, states, and the nation, and contain basic demographic detail such as age, sex, race, and ethnicity.    

Postcensal estimates are produced for each year following a decennial census.  While the intercensal estimates are more accurate, postcensal estimates are the most up-to-date source of population data.  For example, postcensal estimates for a given year are typically released the following year.  Intercensal estimates for that same year won't be available until after the next decennial census count.  The postcensal estimates are produced for incorporated places, counties, states, and the nation and include basic demographic detail such as age, sex, race, and ethnicity.  

Unlike the intercensal and postcensal estimates, which are based on the latest decennial census count of the entire population, the American Community Survey is based on a sample or subset of the population.  Therefore, users should rely on decennial census counts, intercensal estimates, or postcensal estimates for official population totals and basic demographics.  However, ACS estimates provide valuable detail on a wide range of socioeconomic topics not included in the data sources mentioned above.  ACS estimates are also produced for smaller geographic levels than the intercensal or postcensal estimates.  Use the ACS Query Tool to search and download ACS data by topic, year. geography, and demographic detail.  

There are over 130 surveys and programs carried out by the U.S. Census Bureau.  In addition to the 4 mentioned above, other popular data products include the Current Population Survey, Economic Census, and County Business Patterns.  Users familiar with application programming interfaces (APIs) can use our Census API Tool to browse and download any data available through the Census Bureau’s API. 

The Revenue and Fiscal Affairs Office produces annual projections for all SC counties by age and sex. The latest projections are based on population, birth, and death trends from 2019 to 2023 and extend 20 years into the future. These are typically used for state and local planning purposes.