Jane Jacobs: Four Generators of Diversity

 Jane Jacobs is an urban theorist, whose book, The Death and Life of Great American Cities examine the way we look at cities. She equated diversity with liveliness and a good quality of life.

"Diversity, of whatever kind, that is generated by cities rests on the fact that in cities so many people are so close together and among them contain so many different tastes, skills, needs, supplies, and bees in their bonnets."

She identified four generators of diversity:

1. Need for Primary Mixed Uses

"The district and indeed as many of its internal parts as possible, must serve more than one primary function; preferably more than two. These must insure the presence of people who go outdoors on different schedules and are in the place for different purposes, but who are able to able to use many facilities in common."

Commercial, Residential, and Religious buildings are all visible.

Lively districts should contain a mixture of uses, for example, restaurants, offices, residences, museums, garages, upscale retail, lowscale retail, industry, etc. The more different types the better, since that draws more people and more different kinds of people to that location. The connections made by these diverse groups of people form new innovations. Diverse uses also should try to ensure that there is always something going on. Diverse activities should be happening all the time. She gave an example of mealtimes, where a flurry of activity happens at mealtimes, but the rest of the day is rather dull. It is important that people mingle.  People should not be separated by the choice of  overhead walkways or alleyways that are only for deliverymen.



2. Need for Small Blocks
 "Most blocks must be short; that is, streets and opportunities to turn corners must be frequent."

This allows diverse flows of traffic, as well as more locations for businesses. 

3. Need for Aged Buildings

"The district must mingle buildings that vary in age and condition, including a good proportion of old ones."

This creates diversity in income. New buildings need to pay for the cost of construction and are thus only available to the subsidized or high profit tenants. Old buildings are paid off and depreciated and thus can be rented by businesses and tenants with small profits and incomes. Thus new innovative businesses go in old buildings. The mixture of both types allows choice and diversity. 
 
4. Need for Concentration

"The district must have a sufficiently dense concentration of people, for whatever purpose they may be there. This includes people there because of residence."

Just as business and activity spaces must intensely use their land, so must dwellings. These dwelling units should also be in diverse styles and forms. Density is a source of immense vitality due to the large amount of human capital and their interactions.

These generators create an environment that allows diversity to flourish:

"All four in combination are necessary to generate city diversity; the absence of any one of the four frustrates a district's potential."

The Death and Life of Great American Cities is an excellent book and I very much recommend that everyone interested in revitalizing areas should read it.