Canadian coins used to work in the automatic toll machines on the Illinois Tollway, giving you something on the order of a 30% discount. :)
That's funny because didn't Canadian coins always used to stick to magnets? That's why they wouldn't work in a lot of vending machines.
Those Necco candy wafers used to work in the Illinois booths, too.
Not that I remember from my own experience.
My real beef is the I-pass where you are FINED for using legal money.
Maybe they can take pesos, too!