Every city around the globe faces questions of horizontal expansion at one time or another in its life – when and how to do so, and in many cases, how to work with, incorporate, or service neighborhoods that have organically become integral to the municipality. While most – if not all – major cities have formal plans for development and expansion, the reality of expansion (in timing, scale, and structures) often substantially diverges from these visions. So how should a city cope when its population, fundamental infrastructures, and needs expand beyond the plans?
In the northeastern US, where I live, the horizontal expansion of cities is largely constrained by the existence of other cities, towns, or suburbs. While, on occasion, pre-existing towns might be legally incorporated into a larger city framework, the questions of functional integration of informal expansion are often addressed through the development of regional plans and establishment of metro or regional authorities. While such regional administration provides its own set of challenges it also allows for formal recognition, and thus continued support, of informal dynamics of human movement, commerce, and exchange that developed over time – without discarding the fundamentals of local administration which make many smaller towns around major cities compelling place to live.
In many developing countries, the informal horizontal expansion of cities is considered to be one of the biggest municipal challenges. Such expansion is typically driven by rural-to-urban migrations and takes the form of un-titled, un-permitted, self-built communities with very low-incomes that quickly become slums. Because these communities are often established on undeveloped municipal land, the city suddenly becomes responsible for providing services; though the provision of such services may be well beyond their capacity. As many of you will know, approaches to such informal development vary, from wholesale eviction to full titled regularization of title to neighborhood redevelopment.
One of the most interesting contexts that I’ve come across while working on these issues is Ulaanbaatar, which is both the capital of and largest city in Mongolia. Situated in a valley along a river, Ulaanbaatar has expanded through low-density, horizontal growth from a formally gridded city with just over 500,000 residents in 1990 to 1.4 million residents today. Because the rural economy of nomadic herding is not as sustainable as it once was more and more people are moving to the cities – particularly Ulaanbaatar.
The unique situation in Mongolia stems from four underlying factors:
- Mongolia is fundamentally a rural country, and even now approximately half of the population is semi-nomadic.
- A provision in Mongolia’s land law gives citizens the right to acquire ownership of a plot of land for residence, for free, once in their lifetime.
- In order for the state to re-take land for public purposes, they must get agreement from 80% of the affected residents.
- The houses that are built – whether gers (yurts) or larger constructions – are generally relatively well-built to withstand the harsh winter temperatures.
Because most of the urban growth around Ulaanbaatar is from previously nomadic families settling close to the city, it has largely occurred on formally titled land, or land that could be easily registered under the land laws at minimal cost to the residents. But at the same time it is severely underserviced, lacking municipal infrastructure for water, sewage, and heat. The combination of these factors means that the typology of horizontal urban expansion in Ulaanbaatar sits somewhere between the two described above.
Thus, the solution to improving this unique urban environment must include a combination of elements that build on the validity of the established land claims to leverage assets and resources of existing residents, while making space for and prioritizing the expansion of municipally supported infrastructure grids. It is precisely because this complex tapestry must weave together the formal and informal that I find it both fascinating and full of opportunity for new and systemically impactful approaches to urban redevelopment.
 The Dorchester neighborhood of Boston, MA is one such example. Established as a town in 1630, it was annexed in pieces to Boston from 1804 to 1870, and subsequently integrated through municipal infrastructures such as streetcars and educational districts.