Ok. I only know that it's 20 days in advance for primaries and elections, and 10 for local-type things - in Mass.

And, especially when considering people who are sending things through the mail, ~a month seems safer. Because, if your registration form is late, I think you're screwed. I'm not certain about that, however.

I was also told by the local state something or other, when I called about changing what I was registered _as_, that I needed to do it by Oct 2nd. Not 13th.