The closest land port of entry from Boston, MA?

I will drive to the border soon to obtain TN visa, from Boston, MA. Anyone know the closest land port of entry where they processes the TN visas?
Thanks!

Ok, I was told that Derby Line is a good place.
Does anyone know, however, do I need to actually cross the border and enter Canada and than return, or can I just go to the port office on the USA side.
Apparently there is a Canadian law that prevents Canadians to rent a car in USA and then returning it back to USA?!

You can do it at Derby Line but I have to say various people have posted on here that they're pretty strict about TN-1.

You can rent a car in the US and enter Canada provided you've got sufficient evidence the import is temporary. You've got to have all that stuff to apply for TN-1 so it shouldn't be a problem as you should have piles of evidence.

This one comes up quite often on here, occasionally there is a horror story but I've seen so many cars with US plates at rental places over the years I can't see how it can be that big of a problem.

Thanks Steve.
I found one topic here about Derby Line entry point and most people had good experience. It is my first time to apply for TN, as I am switching from TD visa I got few months ago. Anyhow I am open for alternative suggestions.

In fact Derby Line is on highway, it is not easy (or possible) to walk across the border; in case I need to walk and park on the USA side, what other entry point would be good?

http://www.cbp.gov/xp/cgov/toolbox/contacts/ports/ - must be Class A. Type in the State and it will give you a list.

I went to the Derby Line after all. Rented a car and was allowed to enter Canada, spent 20 seconds there, just enough to make an U-turn and returned.
I got TN visa for 3 years, everything was smooth as can be. Thanks again.