Which is not actually a right. Americans have no more a right to travel to Canada than Canadians have a right to come to the US. I venture that more canadians are probably denied entry to the US than Americans are denied by Canada.
It very much depends on who you ask. Some libertarians will say that it hasn't been that long the modern system has been in place. I think since roughly WWI?
The lack of a "right" to enter a country could be compared with the modern lack of a right for pedestrians to walk in middle of most streets. Now and then some people get quite bitter about that.
Which is not actually a right. Americans have no more a right to travel to Canada than Canadians have a right to come to the US. I venture that more canadians are probably denied entry to the US than Americans are denied by Canada.