July 11, 2012
Below the electoral map on our site, there's a feature you may have seen called "The Road to 270". This feature calculates the number of 'critical path' combinations to 270 that remain for either party based on the undecided states in your map, as well as any possible tie combinations. It updates automatically each time you change the status of a state.
By critical path, we mean those combinations that are available to cross the required 270 electoral votes threshold. To take a simple example, let's say Obama has 262 electoral votes on your map, and the only two undecided states are Virginia (13 electoral votes) and New Hampshire (4 electoral votes). While there are two overall combinations there (VA or VA+NH), only one of them is relevant to our goal of 270. Put another way, if you were managing the Obama campaign in this scenario, how much resource would you devote to winning New Hampshire?
The new features include the following:
- Must Win for 270: Displayed separately, these are any states that, if lost, would give the other candidate to 269 or more electoral votes. Therefore any states in this category will be required in every critical path to 270.
- Not Needed for 270: Displayed separately, these are states that are not required in any critical path, like New Hampshire in the earlier example.
- Filtering: For all the states not fitting into one of the above two categories, we now display the number of combinations that include that state. You can check one or more states to filter to only those paths that include all the checked states.
- Totals: The total electoral votes associated with each combination are shown
- Probability: The combinations are ordered by probability of occurring (based on polling averages). Note that probability doesn't necessarily mean "probable". For example, if Obama has 268 electoral votes on your map, and the states remaining are Montana and Kentucky, Montana will appear higher than Kentucky on the list, but we're talking about "improbable" in the case of Montana, and "extremely unlikely" in the case of Kentucky. Note also that when dozens of combinations remain, with multiple states in a combination, almost any single specific path is going to have a low probability, particularly if it involves toss-up states.
The Road to 270 also calculates tie scenarios that are possible with your map. Every remaining state is involved in a tie scenario, of course. The Ties page shows each possible tie scenario and how the states break out between Obama and Romney. These tie scenarios are not in any particular order at this time.
The Road to 270 feature appears when 12 or fewer states remain undecided on your map and neither candidate has reached 270 electoral votes.
Updated every two hours until election day, this map will reflect the probabilistic model used by fivethirtyeight
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