Final answer:
State legislatures originally elected U.S. Senators, but the 17th Amendment, passed in 1913, gave this power directly to the people.
Step-by-step explanation:
Originally, U.S. Senators were elected by state legislatures. This process was changed by the 17th Amendment, which granted the power to elect senators directly to the people. The 17th Amendment was passed in 1913 after concerns over scandals and the influence of business interests on the selection of senators by state legislatures. The amendment aligned the election process of senators with that of representatives, ensuring that both are directly elected by a popular vote.