Cities’ Land Footprint Outpaces Population

An April 14 Washington Post Wonkblog post highlighted the phenomenon of major cities worldwide increasing their developed land footprint much faster than their population footprint.  Using maps from The Atlas of Urban Expansion  prepared by the Lincoln Institute of Land Policy and time-lapse animations prepared by the New York University Stern Urbanization Project, the post argued that transportation advances, falling density, and the rising number of smaller households has accelerated this trend.

Throughout the last two centuries, cities across the globe – as you might view them from space – have expanded in a relatively uniform way: first incrementally, then at a breakneck speed.

In older cities, this pattern has paralleled innovations in transportation. Early 19th century London, Boston or Warsaw could only expand so fast when the main modes of getting around were by foot or horse and buggy. Eventually, streetcars, railways and automobiles changed the geography of urbanization.  …

The maps reflect both the rapid growth of new development and, in some cases, the swallowing up of existing rural communities as urban centers have expanded.

The animations repeatedly show this process gaining speed (and land mass) in the second half of the 20th century.  Writes NYU research scholar Patrick Lamson-Hall in introducing the [animation] project:

This is in keeping with the theory of falling density, which holds that as cities have grown bigger and the world has urbanized, densities have been steadily falling.   As a result, cities require more urban land per person, meaning total growth in the city area is much greater than population growth.

This trend is closely related to another phenomenon: Globally, household growth is expanding much faster than population growth.  That means the literal number of homes on the planet — each requiring land, energy and infrastructure — is expanding faster than the number of people. …

All of these trends — growing urbanization, falling density, rising household growth — together present some big challenges for how we consume resources and land. …

But it’s not necessarily inevitable that urban areas should gobble up land so much faster than they gain population. That’s the kind of thing we can try to plan for.