The 17th amendment is an amendment to the US constitution. It provides that US Senators be elected by popular vote and was written to supersede an earlier article that provided for election of US Senators by individual state legislators. It further provides alterations to the method for filling seats vacated mid-term. It was enacted on April 8, 1913.
Article one, section three of the US Constitution sets forth the original laws regarding the US Senate. This includes the provision of two senators per state, each serving a six-year term and each having one vote. It further provides that such senators shall be elected by the legislature of the state they represent. The 17th amendment provides for the same quantity of senators and votes, and for the same term of office, but it changes the method of election to a popular vote of the people, or electors. It further provides that such electors must meet voting qualifications, which is meant to include qualifications such as age and residency.
Prior to the 17th amendment, the intent of the election of senators by state legislatures was to prevent uninformed voters from electing a candidate who was unqualified or unethical simply because he gave good speeches or made grand promises. The writers of the constitution believed that elected officials, who had experience with the ways and strategies of politics, would be less likely to succumb to candidates whose qualifications consisted of charm more than substance. They also thought that such elected officers would be above bribes, side deals, and intimidation tactics that might be used by some seeking a Senate seat. It was further considered that senators should be free from the stress of campaigning so that they could focus on governing.
That process was generally considered to have worked fairly well until the mid 1850s. The issue of slavery and the associated increase in partisanship and general disagreement is frequently credited with the failure of the old system of Senate elections. Several states simply failed to elect senators for years at a time, causing them to be under- or unrepresented in the Senate. Several elections were contested based on election methodology as well.
In 1866, Congress passed a law to help control the method of elections. This law is often considered the forerunner of the 17th amendment, but while it helped, it didn't help much. Meanwhile, the concept of direct election, which is election by the people, had been rapidly gaining support.
First introduced as early as the 1820s, the first constitutional amendment providing for direct election was proposed in 1893. Every year thereafter, until 1903, such an amendment was proposed in Congress and rejected by the Senate. Direct election of US Senators, and a corresponding process for filling vacancies, was finally passed as the 17th amendment in 1913, almost 100 years after it was first proposed.