New York City is hemorrhaging population at a pace not seen since the 1970s—and the exodus shows no signs of abating. The departures are not, as conventional wisdom holds, struggling families priced out by unaffordable housing: they are young, well-educated professionals earning 13% more than their peers who stay. From hedge fund analysts decamping to Stamford to lawyers heading to Washington, the data reveals a city losing precisely the human capital it needs most. This is the first installment of a rigorous, data-driven examination of who is leaving, where they're going, and what it portends for the future of America's preeminent metropolis.