How big is your city, really?
Ever since the skyscraper came along and introduced the world's metropolises to both vertical growth and stark Freudian symbolism, cities have been built up rather than out. But how big would your city be if all that space that had been added upwards was laid out flat? That is, what if all the above-ground floors were added to the edge of the city, so you could see how much living space there truly was?
One World Trade
Okay, so just so we’re all clear on the concept, to fully demonstrate it, here is One World Trade -- the newest, tallest, free-est building in the US. That teeny black square is the amount of actual ground that it stands on. The red area is the amount of actual space inside the building.
Taking it up a level, here we see the whole island of Manhattan if we did that to ALL the buildings. It is considerably bigger. More than three times as big, in fact, making it just a shade larger than Brooklyn is. Ordinarily, Manhattan’s population density is considered to be the highest of any county in the US (about 70k people per square mile). When you look at it like this -- in terms of the actual living space -- Manhattan is only about as densely populated as Queens (20k people per square mile).
Next up, we took on an entire city. Here’s what it would be like if it we took Chi-Town’s deep dish buildings and spread 'em out nice and thin. After crunching the numbers, it looks like about a full third of Chicago's living space is loftily perched above ground.
By a completely bizarre coincidence, SF is exactly the same proportion as Chicago -- 30.1% bigger -- when laid out flat. Also, a lot more underwater, apparently.
And finally, just to confirm what everyone who lives in LA already knows, that city (or collection of neighborhoods, or whatever) is already as flat as a British apartment -- here she is in all her incrementally larger glory.
And now, a brief word on methodology: So how did we figure all this out? Well, first you take the total land area of whatever place you’re talking about (thanks Wikipedia!). Then, you need to scour the Internet for total inventories of commercial, retail, residential, and industrial floorspace in that area (thanks, dozens of hard-to-find real estate sites!). And finally -- the real trick -- before adding these together, you need to eliminate the ground floor from each building, otherwise you’d be counting it twice. Doing this requires you to know something called the "floor area ratio" (the amount of floorspace a building’s footprint can take up) of each district, and thankfully, government sites usually provide this information. One you've accounted for that, voila!