Final answer:
U.S. Senators were originally chosen by state legislatures according to the U.S. Constitution. The modern day selection process changed with the passage of the 17th Amendment, which made senators be elected directly by the people.
Step-by-step explanation:
The U.S. Constitution originally stated that U.S. Senators would be chosen by their state legislatures. This selection process was in place until the 17th Amendment was passed in 1913, which changed the selection to a direct vote by the people. The change was made due to a series of scandalous elections that caused citizens to resent the selection of senators by state legislatures.