Do Canadian citizens need to show negative Covid results to cross the US boarder?

This is the Peace Arch PARK. Not border crossing. If you mean within the park a COVID test is not needed, all you need is some proof of citizenship. My mom forgot hers and she was stuck there for 2 hours, don't make that mistake.

No, but if you are not an American citizen, you need to be fully vaccinated to cross into the states. And you will be required to have a negative covid test taken in the states within 72 hours to cross back into Canada.