I've been thinking lately on national disasters - those periods and conflicts that inflict irreparable harm to a people. I refer to events like the Japanese and Taiping devastations of China, Barbarossa for the Soviets, the war in general for Poland and Germany, both of Paraguay's major wars and Bolivia's last one, or further back the 17th century religious wars in England and Germany. This sort of war has profound effects on the economic and demographic nature of the population subjected to it; effects that can often play out decades after the supposed recovery. I could easily tangent into the role WWII played in the dissolution of the USSR, but to stay on point....
Clearly the closest the United States ever came to such a conflict, barring early colonial debacles and arguably the Revolution itself, was the War between the States. That said, the event was a lot cleaner and more bloodless than it might have been, a fact starkly obvious to the reader familiar with the above conflicts.
This is not an attempt to screw one side or the other. For that matter, it's not really about the conflict at all - I just know I can't get away without outlining the war first. Nor will it feature the Powers joining in. I am of the school that holds the resulting war would be if anything shortened. It is about America, and Americans.
My apologies to the estate of William H. Seward. I don't actually think he was that bad, in and of himself. He had the makings of a good president, maybe great. But the worst case scenario I see for the war, well, a Seward presidency is the most straightforward POD to get there.
Or rather, the most straightforward secondary POD. The actual divergence is Orthomyxoviridae 1858.