Maine has some snakes including the garter and milk snakes, but these aren't poisonous. Officially Maine, like Alaska and Hawaii, has no poisonous snakes at all. There are stories of rattlesnakes in one very remote area, but these aren't authenticated and it's hard to say how far they should be believed. You may like to have a look at some of these stories and make up your own mind.
Whatever you decide, it seems clear that Maine is about as snake-free a place as you can find in the US.
Whatever you decide, it seems clear that Maine is about as snake-free a place as you can find in the US.