EVERY time a group of residents pools its energies to set about fending off a monstrous development in their neighbourhood, it is an unspoken tribute to the resilient and imaginative writer Jane Jacobs.

Her influential book, The Death and Life of Great American Cities (1961), not only grew from her own success in saving her corner of Manhattan from another large road, but also had some influence in persuading planners that a city’s real economy derives from a series of small-scale, mixed uses.

Jacobs’s bête noire was the Commissioner of Parks, Robert Moses, who, despite his title, urged the building of roads and the destruction of fine buildings. Moses described her efforts as “intemperate and inaccurate and libellous”; Moses’s biographer, Robert Caro, however, calls her “one of the heroines of New York history”.

Her views were not hidebound by theory but were rooted in her own observation, allied with wide reading in history and philosophy.

She was born Jane Butzner in 1916 in Scranton, Philadelphia, where, the daughter of a doctor, she did enough to get by at school, and held imaginary conversations with Jefferson and Benjamin Franklin. Thus equipped, she left school to work for a year as an unpaid assistant on a newspaper, the Scranton Tribune. Any notion of getting a degree paled beside the prospect of New York. As she recalled: “In 1928 I went there, with friends, and we came through the Holland Tunnel and right into the middle of the financial district, on a regular working day, and I was just flabbergasted by the number of people on the street and how they were all rushing around.”

In the Depression she returned there, with her sister, and found work on a metal-trades journal before turning freelance to work for the Herald-Tribune, Vogue and Architectural Forum. She also worked for the Office of War Information and in 1944 married the architect Robert Jacobs. In due course they had a daughter and two sons, and the latter would bring a radical change to their lives.

Jacobs said that her husband taught her enough about architecture to enable her to write on it. Her interest in it was stoked by her horror at some of the rebuilding projects that she reported on. She realised that many projects were neither safe nor interesting — and, moreover, made a poor economic prospect for a city.

She hated to see cities drained of life by corporations whose promise of jobs so often results in the loss of many others. “That attitude — that you can sacrifice small things, young things, and a diversity of things, for some great big success — is very sad . . . One of the most dismal things is when you go to a city and it’s like 12 others you’ve seen.”

She recognised that she had somehow become a character: “During the course of the battle I undertook, at the behest of a committee organiser away over on the other side of Greenwich Village, to deposit in stores on a few blocks of our street supplies of petition cards protesting the proposed roadway. Customers would sign the cards while in the stores, and from time to time I would make my pick-ups. As a result of engaging in this messenger work, I have since become automatically the sidewalk public character on petition strategy. Our street by now has many public experts on petition tactics, including the children. Not only do public characters spread the news and learn the news at retail, so to speak. They connect with each other and thus spead word wholesale, in effect.”

Jacobs calculated that it takes only 100 such characters for word to fan out across a large town and bring people together to create a force.

She relished true community, a complex order she likened to “an intricate ballet, in which the individual dancers and ensembles all have distinctive parts which miraculously reinforce each other and compose an orderly whole”. She gave an evocative account of her street through the day — “I exchange my ritual farewell with Mr Lofaro, the short, thick-bodied, white-aproned fruit man who stands outside his doorway a little up the street, his arms folded, his feet planted, looking solid as earth itself. We nod; we each glance quickly up and down the street, then look back to each other and smile. We have done this many a morning for more than ten years, and we both know what it means: all is well.”

She understood that a city has to be organic, that mixed uses alongside one another bring true prosperity. She wrote of New York that “many a once vital district, having lost in the past a mixture of primary uses which brought attraction, popularity, and high economic value, has declined sadly. This is why projects such as cultural or civic centres, besides being woefully unbalanced themselves as a rule, are tragic in their effects on their cities. They isolate uses — and too often intensive night uses too — from the parts that must have them or sicken.”

She cited Boston as an example: “In 1859 a Committee of Institutes called for a ‘Cultural Conservation’, setting aside a tract to be a devoted ‘solely to institutions of an educational, scientific, and artistic character’, a move that coincided with the beginning of Boston’s long, slow decline as a live cultural leader among American cities.”

Equally opposed to the artificiality of “garden” cities as she was to the grim fantasies of Le Corbusier’s skybound notions, she recognised that a city’s vitality is borne of density properly managed: not gated but organic, with blocks not so long that residents are unable to move from street to street.

As such, the true use of space is a mixture of terraces and mansion-blocks, brownstones being more characteristic of Manhattan than those skyscapers seen from a distance.

It is central to Jacobs’s book that its first 80 pages are devoted to a study of sidewalks — and that she recognised a necessary link between the car and the city, so much so that pedestrianisation schemes often result in aridity: “Unmanageable city vacuums are by no means preferable to unmanageable city traffic,” she said.

More than four decades after its publication, The Death and Life of Great American Cities is as pertinent as ever in the debate about the nature of towns and cities.

Jacobs herself had to leave Manhattan, to help her sons to avoid the Vietnam draft: the family moved to Toronto in 1968 and remained there — having immediately been successful in an attempt to stop another highway.

She wrote more books, such as The Economy of Cities (1969), Cities and the Wealth of Nations (1984) and Systems of Survival (1992).

In the last she deplored the blurring of the distinction between the different ethical stances of goverment and business: the former meant to act in accordance with a “guardian syndrome”, the latter taking a commercial point of view. Partnerships, she said, are in effect, “one of the worst things about urban renewal. It introduced the idea that you could use these government powers to benefit private organisations” — such as the high-interest, never-never payments in public-private finance initiatives.

She also insisted upon a distinction between expansion and development. “They need each other. But they aren’t the same thing. I think perhaps that’s the most important thing I’ve worked out. And if I am thought of as a great thinker, that will be why.”

Jane Jacobs’s husband died in 1996. She is survived by her sons and daughter.

Jane Jacobs, social critic, was born on May 4, 1916. She died on April 25, 2006, aged 89.