Source: U.S. Bureau of the Census, Population Estimates Program (PEP). Updated annually. http://www.census.gov/popest/estimates.html. Census Bureau, 2010 Census of Population, Public Law 94-171 Redistricting Data File. Updated every 10 years. http://factfinder2.census.gov.
Definition: Estimates are made for the United States, states, counties, places, and metropolitan areas within the United States. The timing of estimates and availability of demographic detail vary by geographic level. The schedule of releases is available at http://www.census.gov/popest/schedule.html.
All persons who are "usually resident" in a specified geographic area. The U.S. resident population includes all persons who usually reside in the 50 states and the District of Columbia, but excludes residents of the Commonwealth of Puerto Rico and the Island areas under U.S. sovereignty or jurisdiction (principally American Samoa, Guam, United States Virgin Islands, and the Commonwealth of the Northern Mariana Islands). In addition, the U.S. resident population excludes U.S. Armed Forces overseas and civilian U.S. citizens whose usual place of residence is outside the United States.
Estimates Base - The population count or estimate used as the starting point in the estimates process. It can be the most recent updated Census count or the estimate for a previous date within the same vintage. The vintage year (e.g., V2013) refers to the final year of the time series. The April 1, 2010 Population Estimates base reflects changes to the 2010 Census population from the Boundary and Annexation Survey (BAS) and other geographic program revisions. It may reflect changes from the Count Question Resolution program. See http://www.census.gov/popest/methodology for details for each vintage year
Percent Population Change-- The difference between the population of an area at the beginning and end of a time period, expressed as a percentage of the beginning population.