Jane Jacobs's Principles

Photo by Giles Ashford

Jacobs observed four key qualities of healthy, vibrant cities: mixed uses, frequent streets, varied buildings, and concentration. For a street to thrive, Jacobs argued, there must be a mix of uses. “Intricate minglings of different uses in cities are not a form of chaos,” she wrote. “On the contrary, they represent a complex and highly developed form of order.” When offices exist alongside residences, shops, and restaurants, a neighborhood is active throughout the day and night. This ongoing activity creates safer streets, offers opportunities for businessmen to take hold, and provides residents with necessary services.

“The advantages of short blocks are simple,” Jacobs noted. Walkers in such neighborhoods frequently encounter corners, each offering an opportunity to follow an alternate path. These options create more places for commerce and for encouraging neighbors, and thus contribute to the social and economic life of a neighborhood.

Jacobs articulated her observation that varied buildings could foster diversity in a simple aphorism: “New ideas often need old buildings.” Older buildings, she maintained, made it possible for neighborhoods to support a variety of uses. A mix of old and new buildings allowed small businesses to coexist with larger ones and to populate a neighborhood with people of different incomes.

Photo by Giles Ashford

Jacobs also argued that concentrations of people make neighborhoods safer and allow them to support a greater range of services and uses. “The presence of great numbers of people gathered together in cities should not only be frankly accepted as a physical fact. It follows that they should also be enjoyed as an asset and their presence celebrated.”