From the USDOL
Is the count of unemployed persons limited to just those people receiving unemployment
insurance benefits?
No; the estimate of unemployment is based on a monthly sample survey of households.
All persons who are without jobs and are actively seeking and available to work are
included among the unemployed. (People on temporary layoff are included even if
they do not actively seek work.) There is no requirement or question relating to
unemployment insurance benefits in the monthly survey.http://www.bls.gov/news.release/empsit.faq.htm