Was 1861 Really a Peaceful Transition of Power?

I wasn't going to bother blogging about Lamar Alexander's peculiar boast that today's "peaceful, orderly" transfer of power was uniquely American, figuring that it's just standard patriotic puffery and nothing to complain about. But Dylan Matthews reproduces the chart on the right to show that lots of countries have peaceful transfers of power, and that got my attention. I'm not sure where it came from, but the author appears to think the United States has had 43 peaceful transitions. It's true ...