A short guide to the electoral college – or why maths really matter in US presidential elections

With the general election coming up in Britain soon, Toby and I talk about the "first past the post" system that's used to elect the government in this week's podcast. Toby comments that he thinks this system is unfair – in some outcomes, it could mean that your vote doesn't actually count.

Not exactly the meaning of democracy, is it?

Toby's complaints reminded me that we don't have a completely fair system at home in the US, either, thanks to the electoral college (which has nothing to do with university). 

With this system, a presidential candidate does not necessarily have to win the most popular votes (ballots cast by voters). To win the election, he – or she – needs to win the most electoral college votes, also known as electoral votes. These are cast for the candidate who gets the most votes in each state. 

Electoral college map (Graphic: Scott1554)

So what's the problem? Well, for one thing, a candidate can win the popular vote, but lose the election. That's happened three times, most recently in 2000. Al Gore won the popular vote, but George W. Bush had more electoral college votes – 271 to 266. I don't know if you remember the 2000 election, but the outcome made a lot of people angry.

It certainly seems strange that even when a candidate wins the most votes, he could still lose. How does that work? There are 11 states with 15 or more electoral college votes (click on the map to make it bigger). If a candidate wins the popular vote in these 11 states, then he has 271 electoral college votes – enough to win. But imagine this: to win those 271 votes in the country's most populous states, our candidate only has to get more than 50% of each state's popular votes. The other candidate could get all the votes in the other states, plus just under 50% in those all-important 11 states – and he would still lose.

Like I said, this doesn't happen very often. But it can happen, and when it does, a lot of people look at the US and scratch their heads. I'm still scratching mine.