The number of workers ages 75 and older increased 172% between 1977 and 2007.
Researchers at the federal Bureau of Labor Statistics have published that finding in a review of statistics on older workers.
Employment of U.S. residents 16 and older increased 59% during the 30-year period covered, and employment of U.S. residents ages 65 and over increased 101% during the span, the researchers write.