Looking for an article on voting rationality

I read an article – possibly from an American magazine – a couple of years ago, arguing against the idea that it’s irrational to vote because there’s only a tiny chance that your vote will make the difference between winning and losing. It was saying something vaguely like: you don’t know what number of votes your candidate will need to win nor how many they’ll get other than your own, so you don’t know which individual vote will push them over the winning line, and so it makes sense to stockpile as many as possible, including yours. Only more coherent and substantial than that.

I remember thinking it was interesting but not whether I was convinced. I’ve tried Googling some likely terms but with no luck. Does anyone know what this article was?