The term long term unemployment refers to the segment of out-of-work individuals that have been looking for a job for twenty-seven weeks or more. Long-term unemployment is a component of structural unemployment, which is a shift in the availability of jobs that make it difficult for some workers to find employment.
To be counted among the unemployed, an individual must meet three criteria: they do not have a job; they've actively looked for work in the prior four weeks; and they are currently available to work. Individuals that meet these three requirements, and have not found a job for twenty-seven weeks or more, fall into the subset of the long term unemployed.
The United States Bureau of Labor Statistics tracks long-term unemployment because the Department of Labor's Unemployment Insurance (UI) program provides benefits to eligible workers for twenty-six weeks. Economic conditions that may cause the long term unemployment rate to increase are oftentimes the reason duration of benefits is temporarily extended. According to information published by the National Bureau of Economic Research, over a 25 year timeframe (1990 through 2015), long term unemployed individuals represent between 10% and 45% of all unemployed individuals.
In addition to economic conditions, long term unemployment can increase when there is a shift in the availability of certain occupations that make it difficult for these workers to find a job. For example, the increase in email and other electronic forms of communication have permanently decreased the need for postal workers.