Credit: Juan G. Yunda

A 2015 study comparing the density of 24 metropolitan regions on five continents found that the densest city of all was Bogotá, averaging 25 thousand persons per square kilometre — more than Mexico City or Cairo, andclosely surpassing Lagos and Delhi1. Bogotá was also twenty-times denser than Atlanta and about three-times denser than Paris. However, population density is a metric that does not represent urban morphology effectively, as higher densities can be achieved by housing people in tall buildings with small footprints or in small buildings with large footprints. Thinking about this problem, researchers measured the built form using floor-area ratios, which measure floorspace occupancy and residential share simultaneously. They used boxes to represent the varied urban forms of different cities2 — For example, a tall and slim box represents the residential high-rises of Hong Kong, while a very low and wide box represents the overcrowded informal settlements of Kinshasa. At a density of 196 persons per hectare, Bogotá was best represented by a cube. This meant that the Andean metropolis achieved a practically perfect compactness, or in urbanists' words, a gentle density.

Someone who knows Bogotá will immediately notice that its built form differs greatly from the usual examples of gentle density characterizing central areas of Barcelona, Paris or Vienna. Instead of traditional ‘beautiful’ neighbourhoods, Bogotá has a varied collection of different building typologies ranging from Spanish colonial grids to organic informal settlements, from gated compounds of single-family homes to high-rise residential blocks — all very different urban fabrics closely knit together by a dense network of streets designed for lower intensity use. As a result, Bogotá ranks top amongst both the world’s most traffic-congested cities and amongst the most innovative cities for urban mobility. For instance, as Bogotá was facing increasing density with limited green areas, Ciclovía became a weekly tradition, allowing residents to reclaim congested streets from cars during weekends for recreation and cycling. TransMilenio, the busiest Bus Rapid Transit system in the world, was an urgent intervention brought about to rapidly and affordably solve the transit chaos in the city, upscaling and improving the traditional system of buses. TransMiCable, the public aerial tramway opened in 2019, responded to the challenge of moving people to and from the overcrowded informal settlements located on steep hills. Unintendedly, Bogotá’s mobility solutions became an example for cities in both the Global North and South.

None of this explains how Bogotá grew to accommodate the whole population of metropolitan Chicago in a land area not much larger than Bordeaux. The little-known answer was a zoning code approved in 1979, known locally as ‘Acuerdo 7’. Before Acuerdo 7, Bogotá had a code, similar to that of most US cities, that delineated separate zones for single-family housing, retail and industry. Planners decided to limit city expansion by introducing an urban-growth boundary while increasing density by allowing taller buildings across the city — that is, upzoning. This makes possible the demolition of two-story detached and terraced houses and the construction of five or six story apartment buildings in their place. Many wonder how local planners could introduce such a reform that would face strong opposition from communities, as apartment buildings could potentially lead to a decrease in the value of single-family homes. I believe nobody complained because, the city introduced another innovative urban policy that unintendedly eliminated the challenges of upzoning, so-called stratification.

Stratification was a means to distribute utility bill subsidies from well-off areas to informal settlements. Planners figured out that urban and housing characteristics of a neighbourhood were a good proxy for household income in the absence of a proper taxation database. The city was divided into six different strata, or zones, bordering each other in a ‘redlining’ that, surprisingly, produced little community outcry and became shorthand for social class in everyday speak. For the poorer strata population, the system guaranteed low housing-related costs, such as utility bills and taxes, and for the higher strata population it guaranteed the exclusivity and protection of property values. Forty years later, the system persists in spite of criticism from contemporary scholars and politicians. The city was able to grow vertically and to intensify the occupation of scarce urbanized land while maintaining thin separation of social groups. Moreover, Bogotá has experienced little sprawl or gentrification in comparison to other Latin American cities, as higher-income families transitioned with little anxiety from houses to apartments in the city.

Today, Bogotá is by no means a perfect city. Its problems of congestion and inequality mirror most cities in the Global South, but innovations such as Ciclovía, TransMilenio and TransMiCable, which bring together residents from different social strata, could not be viable without the density and proximity achieved with the stratification system. I draw a controversial lesson: above normative conceptions of urban beauty and social justice imposed by urban planners, people want to live among those they perceive to be like them and to protect their way of living from ‘others’. In current times of global warming and social discontent, Bogotá’s gentle density and spaces of inter-class social interaction are examples that global societies can draw inspiration from. Bogotá demonstrates that it is possible to contain sprawl while living closely together, despite our differences.