By Morgan Clendaniel

New York is a city defined by its public transportation system. It's why, when large parts of it were taken out during Sandy, it was so palpable: It was an easy touchstone for the damage done throughout the city. If the subways weren't working, the city was truly in trouble. This video, which shows one day of the MTA's entire system, shows just why: The public transit that keeps the city running is an insanely complex dance that's also mesmerizing to watch.

There's so much happening in the video that it can be a little hard to parse. It begins at 4 a.m., when there isn't enough activity to make it entirely clear what's going on. As rush hour begins, though, you begin to see the outlines of the subway map and the city taking form. Each square on the subway is coded to the color of its subway line. For instance, you can see a solid stream of green squares--representing the 4 and 5 trains--leaving the southern tip of Manhattan and rolling through the tunnel into Brooklyn.

By 10 a.m., you can fully see the colorful New York subway map (it may be a little hard to recognize, because this map isn't scaled the same way as the squished and distorted subway map). All the colorful squares moving between the subway lines are buses. And if you look to northern Manhattan or western Brooklyn, you can see an occasional lone grey square--a MetroNorth or Long Island Rail Road train--going off to a farther destination.

As we've seen with videos of carpooling in Germany and bike-sharing in Boston, point-to-point transit data makes for an easy compelling data visualization. It's fascinating to watch because our society is built on the premise that we move around a lot, and we've constructed complex systems to serve that need. To watch them in action--especially one as complex and important as New York's--gives you a true sense of human accomplishment.

The intrepid YouTuber who created this video has made simmilar videos for a bunch of other cities--including Los Angeles, Chicago, San Francisco, and Washington, D.C. None are remotely as compelling as New York's, but there are a few below for your viewing enjoyment.

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