We all know that the New York Draft Riots in 1863 were pretty violent, with an estimated 2,000 killed. What if the draft riots got out of hand and spread to other parts of the country. What would happen if the rioters captured Manhattan before the New York Militia and Union Army could arrive?
I thought of an interesting POD to make it more violent.
A week before the riots, the US won at Gettysburg. If we lost Gettysburg, the draft riots would have likely been more violent. This, coupled with the Confederates on the verge of attacking Washington D.C., would force Lincoln to make harsher decisions. This may start riots in many major Union cities.