North America is a great experiment.

Both its nations are primarily English-speaking, Protestant, Northern European immigrant populations, with substantial (and originally dominant) minorities (French in Quebec, Mexican in the US Southwest) and pre-existing Neolithic aboriginal populations. Both were settled about the same time. We tend to think of climate as being a great determiner and distinction, but recall that even today, most of the Canadian population lives within 200 miles of the US border. Ontario is not that much different from Pennsylvania.

Given the inevitable minor differences imposed by history and geography, Canada and the USA are as similar as two neighbors can possibly be. There is only one significant difference: The United States had slavery. The differences between the two nations stem primarily from that.

We are indeed a great experiment, but Canada was the control.