Final answer:
The Congress recognized this in the 1980s and made changes to address the sustainability of the Social Security system.
Step-by-step explanation:
The Congress recognized that Social Security could no longer operate in the future as a purely pay-as-you-go system in the 1980s. In response to recommendations from the Greenspan Commission, the retirement age was raised from sixty-two to sixty-seven and the payroll tax was increased. These changes were made to address the demographic factors of an aging population and the need for sustainability of the Social Security system.