How Young Was the Youngest US Senator?

The youngest US senator ever to serve the country was John Henry Eaton, who was appointed to finish a vacated term as a senator from the state of Tennessee in 1818. At the time of his appointment, Eaton was 28 years old — two years younger than the requirement for elected officials according to the terms of the United States Constitution. Eaton finished out the term and then was elected in his own right and served as a US senator until 1829.

More facts about John Henry Eaton:

• Record-keeping has not always been reliable, so it is possible that no one was aware of Eaton’s correct age at the time of his appointment. In any event, the precedent of appointing someone who was younger than 30 years old to fill a Senate vacancy had been established earlier, with the 1806 appointment of 29-year-old Henry Clay and the 1816 appointment of 28-year-old Armistead Mason.


• Eaton was a prolific writer who authored an early biography on future president Andrew Jackson. The book was published in 1817, a year before Eaton's appointment to the Senate and 12 years before Jackson became president.


• After serving as the U.S. Secretary of War from 1929 to 1831, Eaton served as the territorial governor of Florida from 1834 to 1836. His final governmental appointment was as the US minister to Spain, a position he held until 1840. Eaton and his family remained in Washington, D.C., where he died in 1856.