The Labor Force Participation Rate un the US is the percentage of the Civilian non-institutionalized people who is actively employed or looking for employment.
The Civilian non-institutionalized people are 16 year olds and older, non military and not living in a prison, jail or nursing home.
In the United States the population is about 340 million people. The Civilian non-institutionalized population is 272.8 million people. Out of this people, 169.9 million are in the labor force (employed or looking for work) and 102.9 million are not in the labor force. This means that the labor force participation rate is 62.2%
The people who are not in the labor force are:
People who are unable to work (ill/disabled)
People who are unavailable for work
People who are retired
People who are go to school
People who are taking care of home responsibilities