Source: U.S. Census Bureau  

Release: Annual Estimates of the Population for Counties  

Units:  Thousands of Persons, Not Seasonally Adjusted

Frequency:  Annual

Notes:

Data for "Resident Population" are estimates as of July 1. Data for 1970, 1980, 1990, and 2000 are annual census.

Population estimates are updated annually using current data on births, deaths, and migration to calculate population change since the most recent decennial census. The annual time series of estimates begins with the most recent decennial census data and extends to the vintage year. Each vintage of estimates includes all years since the most recent decennial census.

Source: U.S. Bureau of Labor Statistics  

Release: Unemployment in States and Local Areas (all other areas)  

Units:  Persons, Not Seasonally Adjusted

Frequency:  Monthly

Notes:

These data come from the Current Population Survey (CPS), also known as the household survey.

Civilian Labor Force includes all persons in the civilian noninstitutional population ages 16 and older classified as either employed or unemployed.

Employed persons are all persons who, during the reference week (the week including the 12th day of the month), (a) did any work as paid employees, worked in their own business or profession or on their own farm, or worked 15 hours or more as unpaid workers in an enterprise operated by a member of their family, or (b) were not working but who had jobs from which they were temporarily absent because of vacation, illness, bad weather, childcare problems, maternity or paternity leave, labor-management dispute, job training, or other family or personal reasons, whether or not they were paid for the time off or were seeking other jobs. Each employed person is counted only once, even if he or she holds more than one job.

Unemployed persons are all persons who had no employment during the reference week, were available for work, except for temporary illness, and had made specific efforts to find employment some time during the 4 week-period ending with the reference week. Persons who were waiting to be recalled to a job from which they had been laid off need not have been looking for work to be classified as unemployed.

For more details, see the release's frequently asked questions.