I
I do not know exactly what they do to maintain the relationship but after living in Canada for around 4 years, I understood how USA is important for Canada like for many other countries.
Also,Canada is heavily dependent on South/Latin America for produce and stuff.
There are many other things.
Canada is a beautiful country with less population situated adjacent to USA(most powerful country in the world). They maintain different kind of relationship.
This is from experience. Would not be waste for you to read