37.9 million. This is the number (based on 2007 Population Estimates) of people 65 and older in the United States on July 1, 2007, accounting for 13 percent of the total population. Between 2006 and 2007, this age group increased by 635,000 people. Find more facts relating to the Older Population in our recently released Facts For Features: Older Americans Month: May 2009.