From Investopedia,

The labor force participation rate is a measure of an economy’s active workforce. The formula for the number is the sum of all workers who are employed or actively seeking employment divided by the total noninstitutionalized, civilian working-age population.

The U.S. labor participation rate stood at 61.4% as of February 2021, according to the federal Bureau of Labor Statistics (BLS), which publishes updates monthly. The monthly figures have hovered around 63% since 2013, after a sharp decline in the wake of the Great Recession. In August 2020, there were 13.6 million unemployed, up 7.6 million from the 6 million in August 2019.

One of the many anticipated effects of automation is a decline in the labor force participation rate. For example, in 1850 about 76.6% of men aged 65 and older participated in the labor force. This figure is now down to 23.38%. Among other factors, this decline probably reflects a shift from work to leisure among older people as society got richer from automation.