Voter registration forms are available at post offices, city halls, DMVs and other public buildings. You ll also find the form on college and university campuses, other schools and wherever people are gathering signatures for initiatives. It also asks you to list any party affiliation with boxes for Democrats, Republicans and Independents. This information is used in primary elections when the parties are choosing their candidates. If you do not fill it out, you cannot vote in these elections.
Some states allow all registered voters to vote in primaries regardless of their affiliation.
It may be advantageous to check a party affiliation since it means you can vote in primaries. However, it in no way determines how you can or can t vote. A registered Democrat can vote Republican or any other party and vice-versa. You will also receive election information automatically and you will be informed where to vote in person at the time of the election. While some might consider it a civic duty, registering and voting are really ways that you can control the way we live.