Is there a transponder you can buy/rent that somehow works on all toll roads regardless of what state they are in? It would be great if there is... then one wouldn’t need to think about if they were renting cars in a whole bunch of states. I believe that’s the way it works in Florida... rent a car at Orlando airport and it works on all toll roads in the state but I don’t think it works in other states.
Some states share. Texas and Oklahoma honor each other’s transponders.
An EZ Pass covers most states east of the Mississippi, at least the northeast states. Illinois has an IPass which works in EZ Pass states and Illinois tollroads will accept EZ Pass. The last time I needed to use my IPass across state lines the only road it did not cover was the Ohio Turnpike.