Coverage of Census Population Data

These data are based upon population estimates developed by the U.S. Census. Because these are estimates, they are regularly updated as additional information is received. This update typically occurs annually, but different series are updated and released in different months during the calendar year. As a result, population data for the same point in time (e.g., July 1, 2006) can differ depending upon its "vintage"—that is, when the estimate was made. However, such differences are usually—although not always—small. Further, population counts based upon "population estimates" used here may differ from the counts Census produces in its Current Population Survey. This is because coverage between these two methods differs. The Current Population Survey excludes groups such as the military population, and people living in correctional institutions and nursing homes. These groups are included in population estimates figures.

Over time, there have been changes in how categories have been defined. For example, annual estimates developed prior to the 2000 Census and those developed after differ in the way individuals were classified, so that separate series "pre-2000" and "2000 and later" are needed.

The biggest change is in the way race was defined. Starting with the 2000 Census, individuals were not limited to selecting a single racial category. A person could report that they were "Black and Asian" or "White and Black," while prior to 2000 they had to select a single category.

For the figures from 2000 and later years, the figures reported by racial group here count anyone who selected only that group. For example, a table which reports the number of "Whites" counts anyone reporting "white" alone as their racial identification. The tables covering 2000 on also report how many individuals selected two or more racial categories so the size of this multi-racial population can also be identified. Race should not be confused with ethnic original. Race and ethnic origin (hispanic/non-hispanic) are treated as separate and distinct concepts. In contrast to race, individuals could only select a single ethnic category so that ethnic categories don't overlap.

Racial counts listed in a table covering 2000 or later years as well as ethnic categories add up to the total for the population. For example, someone who reported "Black" would be counted in the Black total, while somebody who selected "Black and Asian" would be counted in the "Two or more races" category. See further details on U.S. Census population estimates.