If your parents have USA visa or are from US visa exempt country, then they can enter usa by land and come back to Canada and complete the landing process. On the other hand if they don't have USA visa or if are not from US visa exempt country, they can enter usa by land and tell them that your parents are flag-poling and they will do a administrative refusal of Admission to USA and then your parents can go back to Canada and can complete the landing process.I have the passport back and I want to do the same thing as my parents are in Canada now. what is Flagpole . how they can be landed without leaving Canada?