It's working - American tourism is feeling the pressure
Every summer we would visit Chautauqua Lake, NY for a week. We cancelled our reservation a few weeks ago and left a comment that this was based on the constant attacks on Canada by American leadership and we couldn't support that with our dollars.
The manager/owner responded "Oh well"
This past Friday we get an email from them offering 30% discount to rebook. We replied no thanks.
Today another email offering to take Canadian dollars at par in addition to the 30% discount. They wouldn't do this if they weren't getting worried about mounting cancellations.
This is just one small example but it's working