Concerns about the co-op program

I've heard that on WaterlooWorks, there are some jobs are out of Canada, such as in the US. My concern is that how can students go for a co-op in the US with a Visa.I know that Canada citizens don't need a Visa to travel to the US (and use a TN visa for work I think). But how about other passport holders (such as Chinese) are they able to work for a co-op in the US? (BTW I have Chinese passport and a Canadian PR card, not sure about if the PR card would help)