We could see a sharp 1-3 days selloff if Democrats win, it will come back quickly. A democratic win may not be that bad, they are going to increase corporate tax from 21% to 28% (Trum lowered from 35% to 21%), but they can roll out much bigger stimulus package and infrustructure spending.
If GOP wins one, SPX will soar through 3800 that is 200% sure.