Of course an individual will only have relationships with a handful of people, whether they live in the suburbs of Houston or in New York. What density does for the individual(or a company) is it gives them access to a diversity of resources, which allows them to be productive. New York and SF are surviving the economic downturn, because they have a multitude of industries. People can change careers in these centers much more easily than in the suburbs.

I am not saying that density is important to certain countries and not in other countries. They are important to all countries. According the UN, the majority of the world’s population now resides in cities. Cities play a bigger role in the global economy than ever before. I agree that certain global cities can be compared with one another, like New York, London, and Tokyo.

However it is no coincidence that we compare New York with London and Tokyo, and not with Sao Paulo and Schenzen. The American economy has more in common with the British and Japanese economies than it does with the Brazilian and Chinese economies. We also have to look at the context of a country, had China stayed on the Maoist path, Schenzen would still be a small fishing village. Given that Schenzen lies just north of Hong Kong, the British handing over Hong Kong to China, also played an important role in the city’s growth.

My point is that there is a correaltion between density and productivity, this applies to all cities. However when comparing across the globe, national factors need to be taken in serious consideration.

I guess I am arguing that the relationship between productivity gains and density is probably logistic (or logarithmic) like in nature. Once, some threshold is met… i doubt the marginal impact on productivity of an increase in density is much greater than zero.

Otherwise, it seems like everyone on the globe would have moved to one place, being that cities have been evolving for thousands of years.

I cant recall where but I have seen studies of social network sites suggesting that “usable” networks (the friends you actually comunicate with) are much smaller than the total number of perosons included the “fried” network. As such, “real” social networks are actually quite small. How many people can one person meaningfully interact with? So once the network gets to a certain level, addional contacts are only marginally advantageous.

On a second matter, to suggest that cross country comparisons are not useful is to suggest that the most relevant unit of analysis in urban ecosystems is the nation state. With Richards work on mega regions and the fact that world wide city systems follow a common distribution (zipf) through time… I feel international comparisons of cities are not only ok… they are necessary.

There is much evidence to suggest that increased globalization makes the city size disribution global in nature… not national. Thus, comparing cities across countries is the appropriate comparions to make. Otherwise, the argument is that density is important only in certain countries and not in others. Which is to say that density is not always positively related to productivity.

I guess, I am thinking that if you cannot compare density and productivity relationships across countries, then your implicitly assuming that other (nation specific) factors are driving productivity, not density.

On the other hand, I think most professional connections are pre-arranged meetings, like lunches or dinners, or events (where you do meet chance people once you’re there). In Houston with its freeway network, it’s no problem arranging a lunch meeting with someone who works 20+ miles away. Or drawing a crowd from a 20+ mile radius to a professional event. In Manhattan, that could be problematically time consuming if they’re even 2 miles away, depending on transit proximity/speed and/or cab availability, speed, and cost tolerance (i.e. would I have a casual lunch with a professional colleague/friend if it requires a $20 round trip cab ride? What potentially serendipitous connection have I lost if I don’t? Might we have become partners in a new business venture? Who knows?).

We may live different lives but I have chance encounters on the street, in Starbucks, driving a new route, anywhere. If serendipity were limited to the Internet we’d be in a very poor place.

Density encourages smaller diverse businesses like Winks Hardware which sells mostly to contractors but is open to everyone and has thousands of things unavailable at Home Depot, or Powells Books where I can browse and find most anything in print used. Yes, I can buy used on Amazon, but I can’t look at it beforehand, I have to pay shipping and wait several days for it.

If I have to do five errands and can find them within a 1 mile radius in Portland and walk between some of them, or a 20 mile radius in Houston where I need to drive and park every time, we’re not comparing one 30 minute trip, but several 30 minute trips.

You have to compare like with like, meaning comparing American cities with other American cities, Indonesian cities with other Indonesian cities. Every city comes in the context of their own country. Jakarta is not as productive as New York because the Indonesian economy is not as productive as the United States. However in the context of Indonesia, Jakarta is the most productive city in the country. For most educated Indonesians, Jakarta is where they want to be if they were to stay in the country.

When we look at growth in different parts of the world, we are seeing more growth in the city centers. Even in the outer slums of most developing cities, there is more opportunity to be had than in the villages in the hinterlands. Simply put, there are more chances to interact with other individuals and develop economic opportunities.

An urban growth boundary is more of a positive than negative. Preserving density and controlling outward growth not only protects the city center from deterioration, but allows the suburbs to be integrated with not only the city but with one another. Such policies are no more imposing as the policies that supported population dispersion. The American suburb is actually quite unnatural, given they would not have been created were not for the construction of the US highway system, subsidizing of mortgage interests, and redlining policies that blocked capital investments into city centers.

> “Furthermore, I also think the question of whether or not imposing density on a place is a positive policy is worthy of consideration. Perhaps the density of places is some type of natural equilibrium that ought not be interfered with.”

Hear, hear!

There may be limits to how much density you need for this, but some density is required.

If what you are saying is true… then the most “dense” cities should be more productive across the board. In other words, the worlds most dense places should always be the most productive.

The problem is that this is not alwyas the case. Many of the densest cities in the world (think Mumbai; India, kolkata, India; Karachi, Pakistan; Lagos, Nigeria; Chennai, India; Bogata, Columbia; Lima, Peru; Kinsaha, Congo; Manila, Philippines; Tehran, Iran; Jakarta, Indonesia; Ho Chi Minh City, Vietnam; Mexico city, Mexico; Saul Paulo, Bazil) are not more productive than many less dense places like: NY, NY; San Fran, CA; London, UK; Paris, FR; ect.

So while density may be important, it is not the whole story for sure. Thus, moving NY to a less dense place may not change anything. I think its near certain that “economic density” matters… but the point of this article was population density and I think that Tory’s time comment holds some merit. Furthermore, I also think the question of whether or not imposing density on a place is a positive policy is worthy of consideration. Perhaps the density of places is some type of natural equilibrium that ought not be interfered with.