I'm not surprised that New England states have some of the highest machine gun ownership rates. There's a lot of wealthy people in that region and it costs a ton of money to own a machine gun.
To get a fully automatic gun, it's going to cost you about $15,000. I think they were banned in '86, but you can buy parts as long as they were prior to '86. So naturally, the price is going to go up. Basically they're not outlawed, but only for the wealthy.