

All images adapted from A Country of Cities: A Manifesto for an Urban America, illustrated by SHoP Architects. Click images to see originals.

Because hyperdensity — defined as density sufficient to support subways — contributes to the health, prosperity, and sustainability of cities, the densification of our built and social environments will to a large extent determine our strength as a nation. Compared to most forms of human habitation, dense cities are the most efficient economic engines; they are the most environmentally sustainable and the most likely to encourage joyful and healthy lifestyles. So, how do we build delightful cities that make us more prosperous, ecological, fit and equitable? Here I will lay out the factors that impede hyperdensity in our cities today, and the conditions necessary to create hyperdense environments in the future, including great design, responsible preservation and sound urban planning.

Sound urban development is the lynchpin of the hyperdense environment. Yet public advocacy for high-density development is extraordinarily low, primarily because its merits are misunderstood. Even among those who appreciate cities, there is enormous confusion about how best to build density. This is largely because the rationale for hyperdensity is often lost on those who should be its strongest advocates. Paradoxically, many of America’s so-called urbanists — broadly defined as urban planners, architects engaged in city building and urban theorists — tend to be enthralled with density yet enraged by real estate development. In fact, today it is a common trope in most schools of architecture and urban planning to believe that density is good but development is bad.

Instead, many urbanists consider European capitals such as Paris and Barcelona as the exemplars of “good density.” And, indeed, with city centers that support mass transit and walkable neighborhoods built at more than 80 units per acre — as is the case in Paris — these are some of the most densely built environments in the world. Since they achieve these densities without, as some would say, ugly skyscrapers built by ugly developers, these cities represent the meritorious urbanity — commonly known as “low rise, high density” — championed by the design and planning fields.

However, these fields tacitly or explicitly consider the growing hyperdense cities of Asia as embodiments of “bad density.” They generally deride places such as Tokyo, Hong Kong and Singapore as being too congested and characterless, the products of mindless real-estate development, inept urban planning and, of course, impoverished (read, non-Western) civic culture. Implicit in such parochialism is the proposition that only Western civilization can — and will — produce superior urbanism, indicating a willful contempt for the fact that many Asian cities are outpacing European capitals not only economically but also in terms of cultural production, mass transit, environmentalism, racial integration and other key metrics. It is unrealistic and irresponsible for any true urbanist to embrace European capitals as models for future development when they are among the most segregated urban centers on earth and have increasingly unstable finances characterized by debt-driven grands projets.



Density beloved and bemoaned. Click image to enlarge.

Cities such as New York, Chicago and Toronto fall somewhere in the middle of the spectrum between beloved and bemoaned urbanism: praised for their picturesque brownstone neighborhoods, criticized for areas where skyscrapers have been allowed to thrive. In fact, Toronto newspapers and blogs have questioned whether that city’s new towers will usher in new urban ghettos. Brownstone Brooklyn, we are told, is sustainable, community-based and charming. Midtown and Lower Manhattan, by contrast, are often derided as the amoral playland of “the 1 percent,” despite the fact that those two business districts generate the majority of the tax dollars that fund the extraordinary array of social goods throughout New York City, including schools, parks and affordable housing.

Missing from these simplistic judgments about good and bad urbanism is an in-depth understanding of the origins of low-rise, high-density environments, not to mention an appreciation of the rationale that will necessitate high-rise, high-density environments in the future. The majority of the historic buildings in Paris, Barcelona and Brownstone Brooklyn were built by the private sector — yes, by real-estate interests and wealthy businessmen. To be sure, as with any great city, these charming neighborhoods are framed by grand public parks, lovely streetscapes, efficient transit systems and dignified foreground buildings. But the much-lauded “good density” in such cities is the building stock itself, which was actually built by powerful development interests and typically fueled by unsavory capital, such as the spoils of colonialism or labor exploitation, and enabled by top-down government. The dripping ornamental wonders of Paris’s Fifth Arrondissement or the stately mansions of Kensington are no less the manifestations of ill-gotten gains than the luxury Manhattan condos that house today’s wealthy and powerful.

Furthermore, it was not the rigors of urban planning but the limits of technology that kept these dense environments low-rise, often to the detriment of their residents. Back then buildings were low-rise not because of regulations mandating streetwalls or streetscapes but rather because elevators and structural steel did not yet exist. As a consequence, and despite their visual charms, many European capitals were notorious for vulnerability to epidemics, fire and squalor. Much of the historic housing stock of New York is characterized by lack of light and air; before the hipster invasion, these dwellings were called tenements and were inhabited by those whom Jacob Riis called the other half.

It is indisputable that technology — the elevator, the subway, structural steel — ushered in a different and fundamentally better way of life for billions. Consider, given the death tolls of historic pandemics, the devastation that the H1N1 virus might have wrought upon Hong Kong if the majority of residents lived in low-density brownstones. Consider the light and air that high-rise dwellers enjoy compared to their counterparts in tenements; in parts of Europe, some people prefer new towers to quaint town centers because, though centuries have passed, they still associate low-rise urbanism with the bubonic plague. When the affluent live in low-rise, high-density housing, the structures are typically wider and more light-filled; poorer tenants are usually relegated to small, dark boxes. And all too many urbanists seem to accept this troubling trade-off, if it means the city can remain tower free, despite the depressing implications for the poor.

Today the global economy demands that we embrace large buildings not just for housing but also for many modern office functions; yet many planning professionals remain fixated on smaller-scale development. They tend to ignore that height limitations have held back the Parisian economy in comparison to the forward-looking redevelopment of London, both at Canary Wharf and within its city center, which is now marked by a series of glistening and respectful new towers by Norman Foster, Richard Rogers and Renzo Piano. There is, in fact, a marked correlation between those European cities that have allowed skyscrapers and those that have successful economies.



Densities unable to support mass transit. Click image to enlarge.



Densities able to support mass transit. Click image to enlarge.



Densified suburbia: the worst of both worlds. Click image to enlarge.

We cannot expect big American cities to reach their potential when the very professions that purport to defend and perpetuate urbanism recoil at the presence of towers. Left rudderless by the experts, we are forced to inhabit the bleak consequences of a poorly regulated marketplace, analogous to a population that must operate on its own cancers due to the confused surgeons who keep cutting away at the healthy tissue. Expanding cities at their edges, even in ways deemed “smart” by planners, is not what we need to do. To the contrary, efforts to “densify suburbia” tend to backfire, creating places like Bethesda, Maryland —mutated environments that exhibit the worst of both worlds, neither urban nor rural, and typified by growing and endless traffic jams despite the presence of token mass transit and a Main Street riddled with chain stores.

As a result, people often and justifiably conflate “development” with congestion and traffic snarls — with images of a bucolic Main Street being transformed into a big-box commercial strip or an office park. For decades, growing U.S. cities have gained density not through strengthened downtowns — through hyperdensity — but through sprawling borders; as a result metropolitan regions have become less efficient — bigger consumers of our resources. In the process, cities have also lost the kind of cohesive order, hierarchy and structure that made them marvels of communal living dating back to ancient Xi’an and Athens.

Urban residents also tend to balk when they hear about “development” because they fear any change to their neighborhoods. Every new proposal has come to be construed as a Robert Moses-like mega-project that will ultimately displace people and tear apart the urban fabric. In cities today many residents channel Jane Jacobs to fight dense, mixed-use, transit-based projects that any true Jacobs acolyte should support. Indeed, the lessons of Jacobs seem to have been translated largely into the very process of protesting, despite the fact that the kind of large-scale urban renewal projects she fought are all but impossible today. Public policy has progressed to the point where environmental and social concerns are just as important as cost and feasibility, and litigation risk now drives major projects far more than the temperament of any all-powerful development czar. And in some cases, regulatory policy and environmental disclosure requirements have become so stringent as to impede the kind of sound, compact development that is in our collective best interest.

By contrast, consider the growing national support for urban light rail, improved subway service and expanded bus routes. It is a conundrum that city residents often support the mass transit networks that hyperdensity requires but none of the development that would make these improvements financeable and sustainable — namely, tall buildings containing affordable housing along transit lines, in communities with shared open spaces, schools and social services. And so we are witnessing misguided investments in urban mass transit, particularly light rail, where there is insufficient density to provide ridership for the system, which results in economic and environmental inefficiencies as well as cries of government waste from transit opponents.



At what densities do Americans live? Click image to enlarge.



A lens for visualizing density at 30 dwelling units per acre. Click image to enlarge.

Hyperdense development is not synonymous with the destruction of a neighborhood’s fabric or “character,” as it is now often called. New York City balanced the two in West Chelsea and Hudson Yards, newly planned neighborhoods that represent Manhattan’s development frontier. In Nashville, developers and designers with Market Street Enterprises have built a beautiful new neighborhood in an underdeveloped part of the city’s core; the Gulch features mixed-use development that enhances the housing options for residents. And rather than opposing it because they feared more people and traffic, neighbors supported the construction of the first LEED-certified district in the South, a compact and sustainable community based on the unique identity of the Music City.

In addition to the benefits of vertical residential neighborhoods, the way people work today demands a range of spaces, from mid-rise manufacturing and commercial structures to high-technology skyscrapers —building types that low-rise neighborhoods alone cannot supply. Today the buzz phrase of office development is “collaborative space,” which is often characterized by large column-free expanses that would be impossible without steel or concrete construction. Access to light and views are valuable, with natural daylight considered key to enhancing worker productivity and lowering the energy demands of artificial lighting. While not always the case, providing natural light and good views often means building tall.

It is important to emphasize, however, that the notion of central business districts comprised solely of office towers is losing ground, and the impact of decades of city planning focused on “mixed-use development” is bearing significant fruit. The proposal for the commercial downtown with little housing or retail — an area that goes quiet at night — is increasingly rare. Across the country, live/work/play urban cores have gained remarkable popularity. Even in large cities like New York, recent decisions by technology companies such as Google to locate in emerging neighborhoods; the resurgence of Lower Manhattan after 9/11; the creation of sports and entertainment venues like Brooklyn’s Barclays Center; and new development on Manhattan’s West Side — all these have upended the traditional office market. As a result, the commercial district near Grand Central Terminal, for example, is now competing with these vibrant new precincts that offer more amenities and nightlife. In response, New York’s Department of City Planning in 2012 launched an initiative to “upzone” the Grand Central area in an effort to spark new development, create more transit-oriented density, and in general rejuvenate the city’s main central business district.

But even in vibrant older neighborhoods, towers of varying sizes are being developed to accommodate entrepreneurs, residents and hotels. And while the adaptive reuse of truly historic buildings is essential, the existing building stock alone will never accommodate the needs of the evolving business or residence, particularly in light of rapid technological and social shifts. Surgical new development remains critical to the rebirth of neighborhoods and the vitality of urban economies. Furthermore, many central business districts nationwide are now anachronisms, with office spaces constructed after World War II that are now substandard. Characterized by low ceilings, byzantine structural grids and wasteful HVAC systems, such places are energy-inefficient (and often induce sick building syndrome). Public policy that strongly encourages the redevelopment of this building stock is critically important if American cities are to remain competitive.



A walkable city of culture and diversity. Click image to enlarge.



Downtown Dallas is already transit rich but does not feature heavy-guage subway service. Click image to enlarge.



A hyperdense downtown Dallas could support rapid mass-transit service and a host of new neighborhood amenities. Click image to enlarge.

The design of new buildings has tremendous significance for cities. While sustainability and functionality are important metrics, innovative architecture has proven to be a significant economic and social driver because of its ability to engender new forms for dwelling, work and repose. Boston’s Macallen housing block by NADAAA, Cleveland’s mixed-use Uptown project by Stanley Saitowitz, D.C.’s World Bank Headquarters by Kohn Pedersen Fox, and New York’s Atlantic Yards transit-based development by SHoP Architects — all exemplify the power of design to generate civic excitement and increase both land and social value. The best of these projects serve their cities as magnificent new structures accomplished within the constraints of budgetary realities. Smart architecture is as smart about money as it is about design. Yet the best urban architecture satisfies more than pragmatic concerns; our best buildings conjure civic delight.

Truly great architecture invites, uplifts and advances its city. A great building invites the public through physical or phenomenological transparency; it shows itself to the city even while veiling surprises within. A great building inspires people through its beauty and material qualities, while enhancing the coherence and contradictions of the street. A great building can reveal a city by exposing its urban structure in new and unfamiliar ways, creating a better collective understanding of its past — and future. A new generation of developers that emphasizes progressive architecture is emerging today.

Yet private real-estate development in the United States has unfortunately been notable largely for its inability to deliver even adequate, much less great, design. Most private development generates horrible architecture for its inhabitants and its city. Even leading American developers lag well behind their competitors in Asia, Europe, South America and the Middle East in terms of embracing contemporary design. Domestic developers claim this is due to cost. Yet a quick survey of developer-driven projects worldwide reveals that it is more a consequence of conservatism and control; that even our high-quality developers tend to favor historicist architecture — meant to look old but in reality brand new — only obfuscates our shared understanding of the contemporary metropolis.

Often, people believe historicist architecture will help preserve urban culture and city fabric. In fact it does neither; culture advances too quickly to be frozen in historicist styles, and truly historic architecture is only denigrated by the false nature of historicism. Historic preservation of real landmarks is of paramount importance, but it is often abused; for the most part, our major cities have recognized and designated most historic buildings, leaving little for landmarks commissions to do but recognize and preserve unworthy structures and districts. For many building owners, historic designation can be more curse than blessing because of the regulatory implications. Furthermore, historic designation, particularly of entire districts, has increasingly become a backdoor method for preventing new development. This is a clear perversion of the nation’s landmarks laws, and can have devastating economic, social, and environmental impacts because of the degree to which it can prevent necessary densification and development.

Overzealous landmark designations also reveal the degree to which urban residents have come to fear change. In some cases, such fear is warranted — a beautiful old warehouse district in Toronto or a brownstone neighborhood in Washington, D.C., should not be besieged with towers. But all across the United States, our urban centers contain low-density areas filled with parking lots and gas stations, driveways and lawns. These areas disproportionately draw upon scarce resources, resulting in expensive infrastructure costs per capita, nonproductive use of valuable land, and intensely negative environmental impacts. Municipalities are justified in intensifying land uses in such areas, especially if they are near mass transit, without being impeded by false claims of historic merit. And if residents are unwilling to allow denser, mixed-use development, they should be made to pay for the real and opportunity costs they impose on a city’s limited coffers.



Hyperdensity leaves nature natural. Click image to enlarge.



Population density and co2 emissions in selected metropolitan areas. Click image to enlarge.



The entire population of the world could fit within Texas’s borders at a density of 25 dwelling units per acre. Click image to enlarge.

This very drama is playing out in Los Angeles today. Mayor Antonio Villaraigosa and other enlightened city officials are fighting impassioned citizens over a plan to rezone Hollywood for denser, mixed-use development in conjunction with construction of a new subway line. As reported in The New York Times, neighborhood associations are claiming preservationist grounds while ignoring the environmental and economic impacts of their parochialism. Meanwhile, a couple of years ago, on the city’s West Side, fear of “Carmageddon” crowded the headlines in advance of the shutdown of the 405 Freeway to allow for the demolition of a bridge — but this proved to be a non-event. All of which suggests that Los Angeles is changing from an automobile-oriented, smog-belching, ever-congested metropolis into an ever denser, more sustainable and thriving city.

In addition to design, the issues of preservation and neighborhood character are, of course, the key concerns of properly planning for new hyperdensity. These include the ability to build skyscrapers when justified by transit, and the capacity of surrounding blocks to accept bigger buildings. Zoning tools are critical for determining building density, massing and land use, but most regulations were created in earlier eras, when we needed to segregate noxious activities. As the United States transitioned from an industrial to a service economy, the need to separate where people work from where they live and play became unnecessary and indeed counterproductive. These days many workers want jobs located near their homes and recreation; sometimes they even want to be able to do everything in the same building. Too often zoning unnecessarily separates uses and over-regulates market forces.

Good planning should be guided by desired objectives rather than prescribed physical outcomes; it should allow for flexible uses, densities and building form in response to evolving market conditions, architectural expression and availability of infrastructure such as mass transit. Cities should unleash the performance-focused power of municipal planning to create public policy and investment that spur private-market reaction, which, in turn, will generate invaluable tax revenues to fund public needs. This is precisely the story behind some of the most successful recent policy-driven urban development, such as the preservation of New York’s High Line and its role as a catalyst for the mixed-use neighborhood that surrounds it.

Density, particularly vertical density, should obviously be planned at the locus of existing transportation. It is also possible to do the reverse, by funding new transportation in conjunction with new development. Similarly, public open space, schools and other critical infrastructure can and should be planned in tandem with hyperdense development. Such multifaceted infrastructure forms the prerequisites for making hyperdensity not just livable but enjoyable. Yet even with the appropriate relationship of public infrastructure to private development, questions remain about the morphology, or formal characteristics, of a hyperdense city. This is a relatively new arena, and we can draw great lessons from international cities such as London and Vancouver as well as emerging urban areas like New Songdo City, outside of Seoul, and Beirut’s new waterfront, which is being constructed in a public-private partnership with Solidere. New York, San Francisco and Chicago provide fine examples of clustering hyperdense towers on grids of streets, but this is by no means the only way that hyperdensity can or should be planned. With rapid urbanization worldwide, experiments in hyperdense morphology will continue, and questions about the best formal qualities of intense, vertically dense, transit-based cities remain open-ended.



How to build the “high-low” city through cap and trade zoning. Click image to enlarge.

My advocacy for hyperdense, vertical cities should by no means be misconstrued as a prescription for everyone to live in an unyielding forest of skyscrapers. It is interesting to note that even Hong Kong, the city most criticized for its relentless tower slabs, is taking steps to enable greater diversity in the size and shape of future development. Variety in building heights — modulation in architecture and scale — is critical for city dwellers to experience both sunlight and delight. Low-rise civic buildings featuring exuberant design, including museums, schools and libraries, are essential. At Columbia University, my students and I have been working on a concept I call “cap and trade zoning,” which would allow the free flow of air rights within an urban district, with an understanding that the overall amount of developable area would be capped in relation to proximity to mass transit. This would result in hyperdensity, to be sure, but would also create a “high-low” city of diverse heights, uses and ages. This concept would strengthen small businesses by permitting owners to sell their air rights, while allowing development to occur on nearby lots. Critics may argue that this approach would result in unpredictable development with varying building scales, to which I would reply “Hip hip hooray!” Much of what passes as good planning today is known as “contextual zoning,” a mechanism through which new architecture is tamed into mediocrity by mimicking a false understanding of the scale and aesthetics of existing neighborhoods. Too often this process allows a lowest-common-denominator mentality to trump the wonders of the unpredictable city. Half a century ago, in The Death and Life of Great American Cities, Jane Jacobs relentlessly critiqued the planner’s urge for control; her critique is no less pertinent today.

While increasing density is exactly what planners and architects nationwide should be encouraging, national and local policy should be promoting hyperdensity as well. Sound urban development projects — created in concert with private developers, policymakers, design professionals and communities —represent the path to prosperity for America’s cities. In planning for hyperdensity, public officials and developers can partner to help cities meet growing infrastructure and service needs without overreliance on the federal government, which has proved far too limited in its ability to address our most pressing problems, from joblessness to global warming.

Permitting the construction of hyperdensity creates what former New York City deputy mayor Daniel Doctoroff has called a “virtuous cycle of economic development”: New residents generate new taxes, which, in turn, equals better municipal services in the form of good schools, beautiful parks and effective policing. This better quality of life brings more new residents and workers, which requires even denser development, which ultimately results in sound municipal budgets, vibrant cities and round-the-clock ridership for public transportation.