I don’t have firsthand experience or knowledge about this, but a quick Google search for “mobile broadband no contract” brought up several matches, including a Verizon offer.
My experience with Verizon’s coverage (cell phone, not broadband) in the Catskills has been very good.
The downside is you may need to purchase a $129 hardware device from Verizon before you can even start purchasing minutes.
I can only try: that’s why there are some companies in Israel that rent these things out for $5 a day or so. Pac-Man is asking whether such things exist in the US as well.
Pac-Man: if you have a 3G/4G phone, you can use your phone as a modem. If it’s not included in your contract, maybe you can add that for 1 month and just pay $20 for once or so.