What was more important for the evolution of political parties in the US, the election of US Senators by popular vote or the suffrage of women? Why? Include the consequences of the Seventeenth Amendment and the Nineteenth Amendment in your answer.
There is no answer to this question that is clearly and objectively correct. One could argue this question either way. My view is that the 17th Amendment did more to change political parties than the 19th Amendment did even though the 19th Amendment is probably more important for the progress of democracy in our country.
Before the direct election of Senators, Senators were elected by members of the state legislatures. This meant that the parties had much more control over who got elected to the Senate. The party leaders could go into the proverbial smoke-filled rooms and decide for themselves who would be elected to the Senate. This was not very democratic, but it was good for giving power to the parties. After the passage of the 17th Amendment, parties had to move out of the smoke-filled rooms and start appealing more directly to the people. The parties lost much of their control over the electoral process. Because of this, the parties became more like they are today.
The 19th Amendment had, in my view, less of an impact on the political parties. This is because the basic dynamics of party politics did not change when women got the vote. Parties were still competing for votes in more or less the same ways, even though the franchise was expanded. Women did not come in and change the ways in which the parties had to operate.
The 19th Amendment was more important for our democracy because it removed an outdated barrier that had prevented half of the population from voting. However, it did not really change the ways in which political parties operated. Therefore, I would argue that the 17th Amendment had a greater impact on the evolution of the political parties in the United States.