Friday, October 23, 2009

What's a City? What's a Suburb?



Pictures from Google Maps


I know what you might be thinking. What kind of question is that? Of course I know the difference between a city and a suburb. Well, I think it's worth making it clear what I mean when I drop these words, since I'll be doing that a lot.

For me, a city, properly so called, is a place that meets the criteria that Jane Jacobs laid out in The Death and Life of Great American Cities (1961). The two most important things that make something a city are density, and mixture of land uses. Density means the number of people or housing units or jobs, or square feet of commercial area per acre of land. So, if you build an apartment building with six stories, as you see in the first photo from my neighborhood in LA, it's much more dense than what you see in the second photo of detached single-family homes somewhere in Riverside, CA.

Density means there are more people in an area to keep an eye on the streets by watching and walking them, and there are more people to support transit (other things equal). It also means a given area can support more jobs, which brings me to my second point: a mixture of land uses.

Planners categorize land uses based on what people do: residential (where people live), retail (where people shop), office, industrial, parkland, etc. Most trips people make are between different land use categories like residential and retail (people going from home to shop), or residential and office (people going from home to work).

When different land uses are close together it's easy to walk, bike, or use transit and thus save money while helping the environment. Density allows for (but doesn't guarantee) a mixture of land uses. In the background of the first (urban) photo you can see a bowling alley.

In a suburb, there isn't much density, and the land uses are generally separated, so almost everybody drives almost everywhere.

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