If a person wants to travel to canada from the US but he only has a green card, can he go without a visa?

This person is originally from a foreign country, he has a green card, though he isn't a citizen yet. So, is a green card enough, or will the person have to get a transit visa?

yes go

If his green card is for a "Permanent Resident Alien", he can go to Canada for a visit. Best bet is to contact your local Immigration Office.

Use your passport and green card to return to the usa

You now must have a pass port to go to canada

BRING YOUR PASSPORT AND ALL AMERICAN VISA AND WORK PERMIT DOCUMENTS!!!!!!!! Check with a Canadian consulate or on the web whether persons from the country of your passport need to get a Canadian visa.

Where in Canada do you wish to go?

Yes, because once you get a Green Card, they give you all ID you need to travel to Canada.Plus, you don't need a visa anyway.

No he can not because he is still a citizen of his native country he is still using a different passport than USA passport.