The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LNS13008636
Source: US. Bureau of Labor Statistics
Release: Employment Situation
US. Bureau of Labor Statistics, Number of Civilians Unemployed for 27 Weeks and Over [UEMP27OV], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/UEMP27OV/, August 30, 2015.
FRED BlogA long-term unemployment problem