The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LNU03008636
Source: US. Bureau of Labor Statistics
Release: Employment Situation
US. Bureau of Labor Statistics, Number of Civilians Unemployed for 27 Weeks and Over [LNU03008636], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/LNU03008636/, July 5, 2015.