My dad was born in Canada and has been a permanent resident of the US for about 50 years (not a US citizen -- he's lazy). I don't think he has returned to Canada once since he started living in the US.
He is planning a trip to Canada and we are wondering if he needs a passport or if his Green Card is sufficient to exit/enter the US.
If he does need a passport, how can he obtain a passport while living outside the country? If it's a requirement that he be physically present in the country to apply for and obtain a passport, that will likely preclude the possibility of him going altogether?