Comparing Density in Cities

LSE Cities is an ambitious project focussed on how the design of cities impacts society, culture and the environment. As part of their mandate they are releasing some visually compelling work, like the  chart below. 




I enjoy the program emphasis on highlighting the diversity of cities and built form around the world. The chart above is an excellent sample of how each cities unique topographical constraints, systems of public transport and infrastructure, and traditions of urban culture and development shape residential densities. As LSE Cities writes

Density differs widely, from the high densities of Hong Kong, Mumbai and central areas of Istanbul and Shanghai to the much lower density pattern of London. Johannesburg shows limited areas of higher density set around a downtown that no longer has a residential population, in the midst of a very low-density sprawl. Istanbul, New York and Hong Kong show how topographical constraints drive densities that rise to ‘spikes’ in Manhattan and parts of the Bronx, Brooklyn and Queens in New York, and in Hong Kong Island and Kowloon in Hong Kong. São Paulo is multi-centred and similar in its overall density pattern to Mexico City, yet São Paulo’s skyline is dominated by high-rise apartment blocks, while Mexico City’s is consistently low-rise, demonstrating that high-density can be achieved with different types of built form.

Looking forward to seeing more from LSE Cities project.


Comparing Urban Footprints Around the World

Matt Hartzell had done a very cool comparison on urban footprints around the worldWhat he is able to show is that there is almost no link between the geographic size of a city and it’s population globally. 

Urban Footprints by Population by Matt Hartzell

Urban Footprints by Population by Matt Hartzell

Also not surprising is that American cities are huge. In fact, Hartzell is able to fit 100 million people into the space that occupies Atlanta.

Visualizing Atlanta's Sprawl by Matt Hartzell

Visualizing Atlanta’s Sprawl by Matt Hartzell

The World’s Biggest Cities Over the Last 6,000 Years

Fun chart via the Business Insider of the largest cities in the world over the last 6,000 years in the “east” (Asia) and “west” (Europe and North America). Click to enlarge.

The population of the biggest cities in the west and east

A clear trend of seeing history’s largest cities in the regions that were the centre of power and industry during their time. Various cities in China dominated before the 18th century, but Tokyo and Japan dominated East Asia in the 19th and 20th century.

Meanwhile in the west the centres of power and commerce shifted between cities in Ancient Mesopotamia and Egypt, to Rome, then to various Ottoman cities and London, before jumping across the Atlantic to New York, and now Mexico City. World history in one chart.

The idea that bigger cities have more crime is now a myth

One of the best things to happen to cities and societies in the last 20 years is the dramatic decline of crime. Canada has reported one of the lowest crime rates since the 1970s. New York City, North America’s second largest city, reported the lowest homicide rate since police began tracking in 1963. The decline in crime also supports the strong growth of downtown living, which is losing it’s stigma as a dangerous place to live.

Why has crime declined so dramatically across North American cities? Mother Jones has a piece that argues convincingly that “gasoline lead is responsible for a good share of the rise and fall of violent crime over the past half century.” In the 1940s most Americans and Canadians began to use leaded gasoline to improve engine performance. This resulted in a huge increase of lead in the atmosphere. In every country, state and city where  lead was banned, 23 years later crime would decline.  No exceptions.

There is even evidence that large cities had higher crime rates than smaller cities because there were more cars and hence a higher concentration of lead in the atmosphere. In fact, since leaded gasoline was banned, big cities have become just as safe as small cities. The idea that bigger cities have more crime is now a myth.

How could lead exposure lead to a prolonged thirty year crime wave? As Kevin Drum writes “even moderately high levels of lead exposure are associated with aggressivity, impulsivity, ADHD, and lower IQ. And right there, you’ve practically defined the profile of a violent young offender.”

Now that we are preventing the release of lead through tailpipes, we need to focus on cleaning up all that lead that is in our soil and homes. As more people move into city centres, where lead concentrations remain the highest, this is becoming even more important. Measuring lead concentration in soil is easy. More cities should study, prepare and report on where the lead exists and make plans to remove it.

Describing Cities, Suburbs, and the Places in Between

by  NASA's Marshall Space Flight Center

by NASA’s Marshall Space Flight Center

Do you live in the slurbs? Work in an Exit Ramp Economy? These are only a few of the concepts identified by Taylor and Lang in a list published in the The Shock Of The New: 100 concepts describing recent urban change. It is a pretty amazing list. I’ve provided the 50 concepts below that have been developed to talk about the edges of cities.

City Lists

Many of these terms appeared in the 50s and 60s as our society and researchers began to grapple with and describe the vast changes at the edge of cities, such as “Rururbia,” Slurbs,” and “Urban Galaxy.” New terms were also invented as the economy of cities and the geography of employment changed in the 80s and 90s,  such as “net of mixed beads” and “edge city.”

The list, which was published in 2004, would certainly be longer today. For example we could add to it Richard Florida’s Mega Regions and Megalopolis, John Kasandra’s Aerotropolis, and Ryan Avents Gated City.  The popularity of some of the terms over time can been seen in the chart below. Exopolis, Edge City and Penturbia seem to be on the rise.  Do we really need all these concepts? It is helpful to urban studies?

Google Ngram Viewer Results for eight terms

Google Ngram Viewer Results for Eight Terms

Taylor and Lang do not think so. In fact, they “suspect that there is more than a little incoherent thinking abroad in contemporary urban studies.”

Clearly, there is a time and place for many of these concepts. Our cities outgrow some and require new ones when older concepts are found lacking. For example, Slurbs seems to have peaked in the 60s, Outer City in the 80s. Overall, a very interesting list that probably tells us as much about the people studying cities as it does about cities themselves.