Based on U.S. Census data, since 1993 the overall labor-force participation rate has steadily grown, reaching a peak of 40.2% in 2010. Even after the economic recession, that is the highest level seen since 1975.
Among those at or over age 55, 46.4% are still in the labor force. While this is a slight decline from the 49.4% of older men working in 1975, it is a marked increase from 37.7% in 1993. The employment rate for women over 55 has also increased since 1993, reaching 35.1% in 2010. Rates among those over 65 have also reached record highs with 31.5% of 65–69 year olds still working, as well as 18% of those ages 70–74.
EBRI cited the need for employment-based health insurance and for more time to accumulate (or replace) assets in defined contribution plans, especially after the 2007–2008 economic downturn, as the most likely causes of this trend. The 2010 Retirement Confidence Survey (RCS) also found that an increasing percentage of workers expects to retire at a later age, and many are motivated by a desire to stay active as well as financial need.
EBRI’s notes on labor force trends are available here.