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We’re Letting You Mess With Our Presidential Forecast, But Try Not To Make The Map Too Weird

The 2020 election might feel like either a dream or a nightmare, depending on who you’re rooting for. But with our new interactive, you’ll at least be able to choose your own election adventure and explore how winning a state or a combination of states will affect President Trump’s and Joe Biden’s chances of winning the Electoral College.

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When you first open the interactive, it’ll show you a map that’s shaded based on our presidential forecast and the 40,000 simulations we run each time we update the model. Deep-blue California, for example, is almost certain to go to Biden, while Trump is favored but not a lock in light-red Texas given their current odds. But what happens if, say, Trump gets some swing states called for him on Nov. 3? How might the probabilities change? That’s what this interactive is all about.

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Unlike other tools that explore paths to 270 electoral votes — many of which are very cool and we like a lot! — ours focuses specifically on how the states are related to one another. Click on Kentucky to turn it red, for instance, and the forecast barely budges, since Trump is almost certain to win Kentucky anyway, and that assumption is already built into the forecast.

Upset wins or decisions in states that our model considers toss-ups could matter a lot more, though. If Biden wins Florida, for instance, his chances1 of winning the Electoral College shoot up to greater than 99 percent, which could be important on Nov. 3 because Florida generally counts its votes quickly and the networks might be able to determine who won the state on election night. But if Trump wins Florida, his Electoral College chances rise to 39 percent, making the race practically a toss-up.

Why such big swings based on just one state? It’s not simply that Florida’s 29 electoral votes are valuable, although they are. It’s also that Florida provides an indication of how other states might vote. Polling errors are correlated, so if Trump wins Florida — where he’s slightly behind right now — he could beat his polls in other states too.

You can also look at how states behave in combination with one another, according to our forecast. Say that Trump wins Florida but that Biden wins North Carolina, another state that usually tallies its votes quickly. This is a good trade for Biden, on balance. His projected number of electoral votes declines from our initial forecast — he’s averaging 345 electoral votes in our forecast as of Tuesday afternoon, and he’d drop to around 309 in this scenario — because without Florida, he won’t have any sort of runaway, landslide victory. But Biden’s probability of winning some combination of 270 electoral votes and therefore the Electoral College increases to 92 percent if he loses Florida but wins North Carolina, because it’s hard for Trump to win the Electoral College unless he wins both states.

In general, Biden has more paths to 270 than Trump, which reflects the fact that he has the polling lead in most swing states. But problems in the Upper Midwest could spell trouble for Biden, as it did for Hillary Clinton in 2016. Trump has a 75 percent chance of winning the election if he wins Wisconsin, for instance.

Another “fun” challenge is to seek out scenarios that could produce a 269-269 Electoral College tie. For instance, if Trump wins Florida, Pennsylvania and North Carolina but Biden wins Michigan, Wisconsin, Minnesota and Arizona, then we wind up with a tie about 12 percent of the time. And before you ask, yes: The interactive does let you choose the winners of each congressional district in Nebraska and Maine, states that give one of their electoral votes to the winner of each district — those single votes are sometimes important in breaking ties.

Our simulations also reflect that states that are more geographically and demographically similar are more likely to swing in the same direction. If Trump wins both North Carolina and Florida, for instance, then Biden’s chances of winning neighboring Georgia fall to just 4 percent. If Biden wins North Carolina and Florida, though, his chances in Georgia soar to 74 percent. By contrast, the candidates’ chances of winning Montana don’t go up or down much based on what you tell the interactive to do in Florida and North Carolina because Montana is so dissimilar to them.

But we’d encourage you to stick to relatively realistic scenarios. The interactive will allow you to do weird things, but only up to a point. Namely, it won’t let you call a state for a candidate if he has less than a 1.5 percent chance of winning it in our initial forecast. But say you want to see what happens if Biden wins Ohio but loses Michigan. You can test that, but be warned: Although both Ohio and Michigan are competitive, that combination of outcomes is rare, since Ohio and Michigan are similar states but Michigan is usually much bluer.

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The model will still spit out an answer, but it’s hard to know how reliable it will be — very few of the 40,000 simulations we run in our forecast will have Biden winning Ohio but Trump winning Michigan. In cases like this where there are few simulations that match the map you’ve chosen, the interactive instead uses a regression-based technique and essentially runs some new simulations on the fly. Still, that could lead to a “garbage in, garbage out” problem.

The goal of our forecast is to figure out which scenarios are most plausible in the real world, and if you deliberately choose some implausible ones, it may be hard to know what to make of the output. Overall, though, we hope you’ll find the interactive both fun and informative — and if you’ve got any questions, please don’t hesitate to drop us a line.


  1. All chances are as of 5:45 p.m. Tuesday.

Nate Silver is the founder and editor in chief of FiveThirtyEight.