Depending on where you’re visiting in the US, toll tags might be an unavoidable part of driving. Furthermore, it can be tricky to know which toll tag you need for what part of the country.
Back in 2012, Congress passed the MAP-21 Act, which required that by the end of October 2016, it be possible to have a single toll tag and account for all federally-funded toll roads in the US. There was no penalty for non-compliance, and no funding was provided, so it’s been slow moving.
Technically, this mostly happened in the form of NATIONALPASS for CA, DE, FL, IL, IN, KS, KY, MA, ME, MD, NH, NJ, NC, NY, OH, PA, RI, TX, VA, and WV. Unfortunately, NATIONALPASS has a monthly fee starting at $16/mo, with $3.50/tag. Note that this crazy thing doesn’t even work on all the toll roads. Washington and Oregon aren’t covered, for example.
Practically speaking, you can get a lot of the country with a couple of toll tags: E-Z Pass, and the North Texas Tollway Authority hub.
For the E-ZPass network on the East coast, you can get one from any of the states or authorities that issue them and they all work together. Someone has helpfully built a comparison matrix here: E-Z Pass System Comparison.
I’d suggest the Massachusetts E-ZPass because the tag doesn’t require a deposit and there are no annual fees or non-usage fees. You’ll need a holder to be able to be able to move this tag between vehicles, so I suggest the JL Safety one, which lasts around five years for me.
If you happen to live somewhere near NYC, I’d suggest getting the NY Thruway tag. Unlike the Port Authority and New Jersey passes, you don’t get charged a monthly fee, but you still get some local discounts. The tricky part is getting one. By default, if you don’t live in the Thruway area, you’ll get assigned to the PANYNJ pass, which might not be the one you want. You can have them manually make you an account, or buy one in person and activate that one. I used the AAA in Nanuet, but I’m sure there are other places that sell them.
For the North Texas system, I recommend the K-Tag that comes with suction cups. There is a sticker version, but it’s difficult to move between vehicles. Like the Massachusetts E-ZPass, you don’t pay anything for it when you’re not using it, though you’ll have to pay $25 for them to send you the movable one.
If you’re looking to get a toll tag for one of these areas that aren’t in one of the big networks, hopefully it’ll become easier soon. I’d suggest going for a movable transponder if you can get one versus the sticker. While NationalPass used to run only $8/mo, it’s now up to $12.50/mo per account, plus $3.50/mo per transponder. This maybe isn’t the worst pricing if you have a fleet, but it’s still free to just get individual tags.