According to FiveThirtyEight.com, if the election is not a blowout, these are the FIVE states to watch on election night: Pennsylvania, Ohio, Colorado, Virginia, and Nevada:
The victory conditions for Obama involving these five states proceed something as follows:
1. Win Pennsylvania and ANY ONE of Colorado, Virginia, Ohio, or Nevada*
2. Win Ohio and EITHER Colorado OR Virginia.
3. Win Colorado AND Virginia AND Nevada.
In other words, watch for these combinations:
- Pennsylvania and Colorado
- Pennsylvania and Virginia
- Pennsylvania and Ohio
- Pennsylvania and Nevada
- Ohio and Colorado
- Ohio and Virginia
- Colorado, Virginia, and Nevada
On Tuesday night, if any of these combinations turn-up blue on the network maps, you know that McCain is basically done, and Obama will be the next president of the United States.
And, of course, if Florida were to go blue early in the evening, Obama would be heading for a landslide.
Prometheus Unbound 
Right. And VA and NC too!
broadsunlit:
According to FiveThirtyEight, IF the election is going to be close, presumably McCain would be winning North Carolina. But the above five states are the combinations that function as firewalls for Obama in a close election.
But you are right, if NC goes blue early on, then McCain is done.
McCain HAS to have NC and Florida, Obama does not.
You betcha! haha, I will be glued to the TV tomorrow night.