With the unemployment rate at a 30-year low in 1999, some have been concerned that the demand for labor may outstrip supply. About 133.5 million workers were classified as employed in 1999: there are several concepts that have been used in the discussion of potential labor supply beyond that.
Unemployed workers represent an existing labor supply, in that they are, by definition, available for work and most are currently conducting an active job search. In some sense, they also represent potential employees in the sense that they have not found a job. In 1999, the number of unemployed averaged 5.9 million.
Moving beyond the unemployed to look for potential workers, 4.6 million people outside the labor force reported that they wanted a job. They were not actively looking for work at the time of the survey for any of a number of reasons including school, family responsibilities, and discouragement about their employment prospects.
Even beyond this possible source of labor, there are quite surely conditions under which some of the 63.8 million persons who are not in the labor force and report that they do not want a job might enter the labor market. Finally, there is a fresh supply of labor that originates from growth in the working-age population.
These data are the product of the Current Population Survey. The labor force is the sum of the employed plus the unemployed, as officially defined. For more information, read "Labor Supply in a Tight Labor Market," (PDF 29K) Issues in Labor Statistics summary 00-13, June 2000.
Bureau of Labor Statistics, U.S. Department of Labor, The Economics Daily, Labor supply in a tight labor market at https://www.bls.gov/opub/ted/2000/jul/wk3/art05.htm (visited November 30, 2022).