| President | Years |
| 1. Theodore Roosevelt* | 42 years 10 months |
| 2. John F. Kennedy* | 43 years 7 months |
| 3. Bill Clinton | 46 years 5 months |
| 4. Ulysses S. Grant | 46 years, 10 months |
| 5. Barack Obama | 47 years, 5 months |
| 6. Grover Cleveland | 47 years, 11 months |
| 7. Franklin Pierce | 48 years, 3 months |
| 8. James Garfield | 49 years, 3 months |
| 9. James K. Polk | 49 years, 4 months |
| 10. Millard Fillmore | 50 years, 6 months |
*Youngest President to assume the office. He was appointed after the assassination of William McKinley in 1901.
**Youngest President elected to the office