But you're Mikey. You are known by all governments as the traveler and don't require proof. "Passport, you don't need my stinking passport."
They know me too well
it's a coin toss, but they're much more likely to require it now than they used to.
i used to cross the canadian border four times per year and never needed anything more than a driver's license until post 9/11 when they tightened border security. now that i carry a passport which contains my work visa i'll never have the opportunity to test the limits again.