Illinois has open primaries and you don’t need to register a party when you register to vote; but you can still register with the parties themselves. I also grew up in South Dakota, which has closed primaries, and you do fill out an party (or not) when you register to vote there, or at least when I turned 18 you did.
I’m conservative in the sense of opposing change, especially to our political system. Not all change, but my default stance is “don’t fuck with it”.