Nearly all US card issuers don't do chip&pin, it's chip&signature (yes, useless, I know). So the gas stations have little incentive to upgrade since there's nothing to sign. Another poster on this thread suggests that non-EMV chip transactions (which are the vast majority in the US right now) aren't any more secure than a mag strip swipe, so there's not much of a benefit.

I'm not sure, but I'd expect that if you don't have a US zip code you can just go inside and use your card with the cashier.