It built the city. Now, no matter the cost — at least $100 billion — the city must rebuild it to survive.

It was the arrival of the subway that transformed a seedy neighborhood called Longacre Square into Times Square, that helped turn a single square mile surrounding the Wall Street station into the center of global finance, that made Coney Island an amusement park for the masses. It was the subway that fueled the astonishing economic growth that built the city’s iconic skyscrapers. Other cities had subways, but none threaded through nearly as many neighborhoods as New York’s, enabling it to move large numbers of workers between Manhattan and the middle-class boroughs — a cycle that repeated itself every day, generating ever more wealth and drawing in ever more people.

We will run 8,477 one-way trips over the course of a day. We hope to have 8,477 on-time trains. We’re not going to do it today.

Some cool photos, too.