What documentation does a Canadian green card holder, living in the U.S. need, to travel to and from Canada?

Also, my dad has had the same green card for about 30 years. Does he need to have it renewed? I was told he needs to become a U.S. citizen in order to get a passport, Does he even need a passport? It’s very confusing to me.

What documentation does a Canadian green card holder, living in the U.S. need, to travel to and from Canada? Read More ยป