Is your political party affliation considered public records for anyone to see?

I was on my states secretary of state website looking up voter information for this upcoming election and noticed something odd. Under the "find your poll location for the election" section, all you have to do is type in your name, city, and birthdate to find out your voter info. It does not show any personal info, however it does show what your political party affiliation is if you have one. Is your politcal party affiliation considered public records? The reason I ask is because anyone who wants to could log on and type in your name, city, and birthday and find out what your political party affiliation is.