The Answer:

Thanks for e-mailing Information Please. According to Article I, section 3 of the U.S. Constitution, senators were to be chosen by the legislatures of their respective states. The 17th Amendment to the Constitution, however, dictates that senators are to be directly elected by the people they represent. (It also established procedures to fill vacancies in the Senate left by resignation, impeachment, or death.) It was ratified in 1913.

—The Editors