On upper population limits in Manhattan

Amy O'Leary's New York Times article "Everybody Inhale: How Many People Can Manhattan Hold?" isn't just of interest to New Yorkers. Manhattan is arguably the paradigmatic metropolis of the modern world; the question of how many Manhattanites can live, sustainably and in a reasonable degree of comfort, in that territory is universally relevant.

As crowded as the city feels at times, the present-day Manhattan population, 1.6 million, is nowhere near what it once was. In 1910, a staggering 2.3 million people crowded the borough, mostly in tenement buildings. It was a time before zoning, when roughly 90,000 windowless rooms were available for rent, and a recent immigrant might share a few hundred square feet with as many as 10 people. At that time, the Lower East Side was one of the most crowded places on the planet, according to demographers. Even as recently as 1950, the Manhattan of “West Side Story” was denser than today, with a population of two million.

By 1980, with the subsequent flight to suburbia, the population fell to 1.4 million. Then crime dropped, the city strengthened economically, and real estate prices started a steady climb, defying broader downturns in the economy as any dip in the market came to be viewed as a buying opportunity.

But those numbers measure Manhattan at its sleepiest, literally. Census figures count only residents, neglecting, as E. B. White famously wrote, “the New York of the commuter, the city that is devoured by locusts each day and spat out each night.”

If a whole city can be created and destroyed in a day, Manhattan comes close. During the workday, the population effectively doubles, to 3.9 million, as shown in a new report by the Rudin Center for Transportation Policy and Management of New York University. Day-trippers, hospital patients, tourists, students and, most of all, commuters, drain the suburbs and outer boroughs, filling streets and office space with life. Wednesday, it turns out, is the most populous day of the week, and special events, like the Macy’s Thanksgiving Day Parade, push the total past five million, offering a glimpse of what an even more crowded Manhattan might feel like.

So if Manhattan’s slow but steady growth continues — and there’s no sign it won’t — how many people can it handle? Answers to this seemingly simple question could fill enough pages to pack a spacious studio apartment, but a quick helicopter tour of future scenarios for Manhattan’s growth shows a tangle of towers and trade-offs.

O'Brien notes that Manhattan's fabric will certainly change radically even with the predicted growth of a quarter-million people by 2030. Low-density areas will be filled, and the skyline is going to rise substantially.

These days, Ed Glaeser, a Harvard economist, inevitably comes up in conversations about how cities should grow. In his recent book, “Triumph of the City,” he makes an argument — which many consider persuasive — that dense places are uniformly better and more interesting than emptier ones, and that they should be allowed to develop unfettered, even if it means building towers where brownstones once stood.

Affordability is the first reason. If you build up, he says, housing prices will fall and more people will be able to live in their own sliver of Manhattan sky. And that’s a good thing, Mr. Glaeser adds, since the energy of all those newcomers will fuel innovation and entrepreneurship, attracting talent and growth to create a virtuous circle. From energy-efficiency to life expectancy to finding a date or something to do on a Saturday night, Mr. Glaeser argues that denser places have the edge.

He’s all for sacrificing charming stretches of the city for more residential space. He favors preserving noteworthy architecture, but suggests a cap on the number of protected buildings at any one time. If you want to protect a new building, he says, another should come off the list.

“There are certainly individual buildings that I feel sentimental about,” Mr. Glaeser said, recalling the memory of watching snow fall on the brownstones and the old Magyar church across the street from his childhood apartment on 69th Street between First and Second Avenues. “Sure, I would feel a little bit sad if that was torn down, but the upside of having thousands more people getting to enjoy New York would outweigh my personal feelings.”

Mr. Glaeser thinks restricting building height is fundamentally unfair. He has proposed scrapping the city’s permitting process in favor of “impact fees” that developers would pay to cover the infrastructure costs associated with their buildings. So if somebody wanted to build a 50-story building, he or she would simply put up the money required to support its water, sewer, power and so forth.

O'Brien concludes that the ultimate upper limits to population in Manhattan may be very high, so long as the city is willing to support investment in innovative solutions to infrastructure. She invokes the memory of the Kowloon Walled City of Hong Kong, a very high-density enclave in that high-density city that was demolished in the 1990s. If Manhattan had the Walled City's population density, it would support 65 million people.