One of the most important things they do is organizing the competition by choosing candidates to run under their label. This is also affected by how states organize their ballots. Parties also help to unify the electorate and moderate conflict, as well as help organize government and turn preference into policy.
At first, Americans were skeptical because they feared Alaska was a wasted opportunity and that they paid for something that was useless. However, when it was found out that it's abundant in gold, everything changed.
They had to help rebuild the south enforce the ban of slavery.