Umm, so how does that explain why the U.S. economy is doing so well right now when the Republicans control both houses of Congress and the White House?

Maybe, just maybe, the main reason why both the Canadian and U.S. economies are doing so well is less about any political ideology and more about the fact that we happen to be near the peak of a current economic cycle, just as we were 9 to 10 years ago.  No surprise give that economic cycles are pretty consistently (since WWII at least) about 9 to 10 years in length.