Thanks, that put me on the right trail for what I was looking for. If I'm reading things right, it went about as far as it could. The area effected was on the the Canada-United States Eastern interconnector and Chicago was on Interconnected Systems Group. Unless we get someone who knows more, and can say if I'm right or if it were possible for the failure in CANUSE to cascade over to ISG, I'll assume it's not possible to blackout Chicago as well.Read here & there that even today the US power grid is too fragmented or compartmentalized to cascade outside each regional grid. One magazine article described 46 discrete regional grids in the lower 48 states. Some large & multistate some small & covering isolated areas. Perhaps there dis a expert at hand that can provide more detail on this?