As a now senior, I have crossed the US-Canada border literally hundreds of times by air, car, rail and bus, on business and for pleasure. One's treatment in either direction can be influenced by everything from current events to the officer's mood on a given day. Citizenship and purpose of visit are also factors. In my experience, Canadians are generally well-treated by US CBP and although I've had some terse conversations with American officers I've never had one be disrespectful or impolite. I suspect the reverse is true for Americans heading north, since CBSA officers tend to be very confrontational towards their own citizens. Depending on the leaning of the Canadian Federal Government the focus changes from drugs, to vaccinations and the current obsession - guns, leading to the strangest question I've been asked when returning from Florida last March: how much ammunition I had bought and was bringing into the country. I do not own a gun and have never had a need for ammunition, so was completely dumbfounded by the randomness of the question. "You were in Florida, weren't you?" has been a joke ever since.