EZ-Pass. New York or Massachusetts account?

[Dave5143]

This summer we plan to take our travel trailer down the Eastern Seaboard and I expect to run into a few toll-roads on the way so I plan to set up an EZ-Pass account in one of the states that offer no-cost transponders. So far it looks like either MA or NY will fill the bill.
My question is this: Sometimes I will have four axles (while towing) or two axles (while visiting sites), will I need two transponders or will the system automagically charge the correct amount based on the number of axles as I go through the toll station?
I believe NY offers two transponders but I'm not sure about MA.

[schlep1967]

I would suggest checking the ez-pass website in each state you are considering. Here in PA you would need one transponder. In your online account you would enter your license plate for your vehicle and your license plate for your trailer. When you go through the toll booth the sensors determine how many axles and what class you are going to be charged for and the photo of your license plate and the transponder determine your account that will be charged.

[RobWNY]

I have two New York Transponders. One for when I'm towing our 5th wheel (4 axles total) and one for when I'm just in my truck. They work fine and I've had no issues. The only place I had to use it outside of New York State was in West Virginia on the turnpike. Your trip may take you to other toll roads. We are in Florida for the winter and not every toll road accepts the EZ Pass so I got a Sun Pass also. If you decide on doing the same as I did, just make sure you mark each transponder so you know which is which. Ours look identical.