Tom Cotton, elected in 2014 to serve in the U.S. Senate from Arkansas, is the youngest member of the Senate in the 114th Congress. Cotton was 37 years old at the time of his election to the Senate.
The youngest person ever to serve in the U.S. Senate was John Henry Eaton, who assumed a seat in the Senate in 1818 representing the state of Tennessee. Despite the Constitution requiring that a member of the Senate be at least 30 years of age, Eaton was only 28 at the time of his swearing-in. Due to poor record-keeping at the time, nobody knew or asked Eaton's exact age.