Little travel tip that I, as a Canadian, learned years ago entirely by chance.
If you encounter this security system in the US (still mostly as gas pumps) - 99.5% of pumps will allow Canadians to use a "zip code". Take the first 3 numeric digits in your Postal Code, and add "00" to the end, making a 5 digit "zip code". Works like a charm almost every time. I've only had it fail once. And they do actually use this as a security code, I've tried 55555 and 90210 and nothing else will work. But this one does.
I'm stunned that this little tidbit isn't all over the Canadian news, considering how many of us travel to the US (especially in our cars!).