McKinley was an enormously important man. He single-handedly set the US on an imperial course, for good or ill. His one decision, in 1898, to hold on to the Philippines put the US in the middle of the great power conflicts in East Asia. That was much more than the fluttering butterfly setting the course of the future by chance. He made a choice, overnight, that set the course of world history.
McKinley and Polk are very underrated presidents. I guess the folks in Humboldt County California hate veterans. So sad.