As another aside, in 2017 my wife and I visited Glacier National Park, MT. We did not bring our passports as we didn't
think we would have the time to visit Waterton Park or the International Peace Bridge.
But, as it turned out-we decided to drive up to the small Canadian/U.S. Border station called the Chief-Waterton station.
The Canadian Inspector, a Mr. Blackthorn asked our nationality and wished to see our passports.
As a retired US INS/ICE Special Agent, I always carry my badge/retired credential. There were no other cars behind us.
The Inspector had a bemused look on his face as I also showed him a card given to me by an RCMP Constable "in case I ever needed it in Canada".
At this point, Mr. Blackthorn explained that HE decided who was allowed to come into Canada, even those undesirables with passports.
Then he asked if I was armed, and I replied not at present-my pistol was back in our camper at Glacier Park. He then said:" Welcome to Canada, stay as long as you like." A nice welcome to Canada.