Who is eligible to vote in the Massachusetts primary March 3, 2020?

Any registered voter. You always have to register first, providing proof of residency. Then all you need is your ID on voting day. 

All one needs to do is declare, and they can vote for the side they declared. Then, for people like myself, we have to remember to go back and put down we are un-enrolled again, or we stuck with whichever party we declared. 

I would like to see all opened up to everyone, no declarations of party, no party designations on ballots.

Russians and North Koreans.