What causes millions of people to be listed as over 100 years old in the Social Security database?

The Social Security database contains millions of individuals listed between ages 100-159 due to missing birth date data. When exact birth information is unavailable, the system defaults to May 20, 1875 - a date related to the Convention du Meter held in Paris which established international standards. This default setting explains why so many people appear to be approximately 150 years old in government records. When officials can't determine someone's exact birth date, they use this placeholder instead of leaving the field empty, resulting in these statistical anomalies. This issue highlights significant data management problems within federal government systems.