As of 2017, the youngest US president was Theodore Roosevelt, who was only 42 when he took office.
Kennedy was the youngest elected US president.
Theodore Roosevelt
Technically John F. Kennedy was elected the youngest but the youngest president in office was Roosevelt. (Roosevelt was elected Vice President in 1900 and became President when President William McKinley was assassinated.)
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Theodore Roosevelt was the Vice President under William McKinley and was the youngest president to hold officer when McKinley was assassinated. John F. Kennedy was youngest president elected to office.
The youngest person to serve as President of the United States was Theodore Roosevelt, who assumed office at the age of 42, following the assasination of William McKinley. John F. Kennedy was the youngest when elected president and youngest who died.
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Bill Clinton (46)
Jhon f kennedy is the youngest president till date.
Both the youngest U.S. Vice President, John C. Breckinridge, and the oldest, Alben W. Barkley, were from Kentucky.
Chief Justice John Marshall was only 45 years old when President Adams appointed him to the US Supreme Court in 1801. Marshall served on the Court until his death in 1835, making him not only the youngest, but the longest-serving Chief Justice in US history.