Last night I was watching a classic episode of the Simpsons where the news anchor mentioned Americans had become so overweight that they could fill the Grand Canyon two fifths of the way up. But, can they? I mean, sure, 35.7% of American adults and 17% of American children are obese, but the Grand Canyon is, in fact, quite grand.

Let's take a quick look at just how large the Grand Canyon really is. At 433 km long and up to 29 km wide it is one of the largest fissures on Earth. Add to that a depth of 1.6 km and you've got yourself one hell of a canyon.

The average width of the Grand Canyon is 16 km. That means the Grand Canyon takes up about 6,928 km2 or 6,928,000,000 m2.

Now, how about the Americans. There are 317.8 million of them. That's a lot of people. Let's say each person needs at least an area of 1 m by 1 m to stand comfortably. If they all bunched up together, Americans in total would take up about 317,800,000 m2. This means you can fill the Grand Canyon with the US population 21.7 times. That's nowhere near filling it two fifths of the way up, of course. Even if donut consumption got so far out of hand that every American was twice their current size, there would still be room to spare.

The city of Manilla is the most densely populated city in the world with 42,857 people living on each km2. If we built a city inside the Grand Canyon for every American citizen to live in, it would be slightly more densely populated with about 45,872 people living on each km2. I'm not sure if Americans would want to live in a city that densely populated, though, since currently the population density of the U.S. is just 34.9 people per km2