Check Out the Age Search Service at the Census Bureau
The Census Bureau is authorized to release certain census records for individuals in order to provide legal confirmation of information such as age, place of birth, and so on.
The information can be released for official reasons, such as passport applications or for social security. But it can also be released for other reasons, including genealogical (family history) research.
Head to census.gov/genealogy and click on the menu item for "Age Search" for full details.