How to handle jumping between US and Canada

[nuru05]

We are about to be heading from Huron to Erie in the next week or so and I am not quite sure how to handle jumping between countries. I know I need to call Canada and do the check in over the phone, but how does it work if we stay in a Canadian marina one night and then an American one the next night and so on? Do I need to check back into the US? How exactly do I do that? Then do I need to check back into Canada if we anchor in Canada on Lake St clair or Lake erie a few days later?