The Great Recession entailed a huge rise in unemployment; that is easy to track, as it is prominently featured in the monthly Bureau of Labor Statistics releases and is soon thereafter up on the St. Louis Fed FRED data site. Almost as well known is the rise in workers on (involuntary) short hours. That sort of correction is standard, reflected in the "U-6" series of "alternative measures of underutilization."
During the current US recession workers also dropped out of the labor force in unprecedented numbers. While that is a major component of adjustment to business cycles in Japan (and unemployment a smaller component), that has not been the case for the US. During the 2001 recession, employment as a share of the population for the middle of the labor market (ages 30-54) fell by 1.7 points. In contrast, between January 2007 and January 2010 the ratio fell by 5.1 points.
During the past decade, however, the age composition of the population shifted markedly; above all, the baby boomers are now entering retirement. This makes it more difficult to summarize in a single number. But it also turns out that the dynamics across different cohorts are quite different. My own prior was that the Great Recession led to a wave of early retirements, which would show up as a drop in the ration of employment to population. In fact, the ratio rose rather than fell.
This brief note focuses on presenting the data.