As liftoff approaches Tuesday evening, the Signal will be focusing (like everyone else) on a small handful of states whose outcomes are not certain or nearly certain well before polls close. Here's a viewer's guide:
The no-drama states
There are 37 states, plus Washington, D.C., who we consider certain for one candidate or another. President Barack Obama controls 14 states and D.C., totaling 186 electoral votes. Gov. Mitt Romney controls 23 states, totaling 190 electoral votes. Virtually every news organization agrees on this list, with only minor variations. The only way Obama or Romney picks off one of these states is if the polls are wildly, wildly wrong and the entire country has shifted dramatically to one side.
The only-a-little-drama states
Seven more states are leaning hard toward one of the candidates (poll closing times in parentheses): Pennsylvania (8 PM ET), Michigan (8 PM and 9 PM ET), Minnesota (9 PM ET), New Mexico (9 PM ET), Wisconsin (9 PM ET), and Nevada (10 PM ET) are leaning heavily toward Obama, for a total of 67 electoral votes. North Carolina (7:30 PM ET), with 15 electoral votes, is leaning heavily toward Romney.
If there are no surprises there, that gets us to 253 electoral votes for Obama and 205 for Romney. Therein lies the central challenge that the Romney campaign has faced since the beginning.
The lots-of-drama states
Six states remain that will probably not be called for hours after the polls close. They are: Virginia (7 PM ET), Ohio (7:30 PM ET), New Hampshire (8 PM ET), Colorado (9 PM ET), and Iowa (10 PM ET) and Florida (7 or 8 PM, depending on county.)
So … who's going to win?
Currently, we predict the following scenarios, each with a certainly likelihood of panning out:
The biggest question early in the evening is whether polling appears to be on track. If the results in Virginia align with Obama's narrow lead in the polls, our confidence in our prediction that he will win the election will grow. The picture is less simple if the results do not agree with polls. A narrow victory for Romney in Virginia would bode very well for him in Ohio, but it's not as simple as adding two points to Romney's column in every contested state.
We'll be looking at three main data sources: exit polls, state-by-state prediction markets, and detailed state maps of the returns. We'll be updating a post on our predictions throughout the night. Stay tuned!
David Rothschild has a Ph.D. in applied economics from the Wharton School of Business at the University of Pennsylvania. Follow him on Twitter @DavMicRot