You asked — Wonder if aluminum foil works? :)
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In Texas and Oklahoma, they have these boxes that charge the toll on the Toll Roads, automatically, as you drive at normal speeds on the highway, right through the toll “gates”.
They supply you with special cellophane-type bags (you can see through them, slightly) that will shield the signals and prevent these devices from working. This is for when people want to pay a toll manually, and not use the “Pike Pass” (in Oklahoma) and the “TollTag” (from NTTA; North Texas Tollway Authority).
So, you can use one of their bags, for that purpose, too.
This is straying over the border into bizarre. I am supposed to keep my passport and passport card in a cellophane bag and whip it out that way? That would get me a secondary inspection for sure. I will stick with my cute tin-foil hat and hope for the best. And why would anyone not want to use their automatic turnpike pass?