Upvote:0
Yes, Except for visitors who may enter Canada with proof of citizenship, an eTA or a temporary resident visa depending on their nationality, all other temporary residents must hold valid permits while in Canada, which must be applied before arrival, on arrival or after arrival.
Upvote:9
Yes. American permanent residents ("green card holders") are exempt from the visa requirement in Canada, but a US visa does not have the same effect.
Source: http://www.cic.gc.ca/english/helpcentre/answer.asp?q=1020&t=16