It flourished in the United States between the beginning of the century and the late 1960s. After this date the internal contradictions involved in making these documents have become ever more apparent, and as a result these plans have lost much of their authority. First of all, those who choose to participate or testify are often motivated by intense feelings on a single issue and can easily exert influence in the planning process out of all proportion to their numbers. More importantly, the process of inviting comment from existing residents of any given area does nothing to ascertain the wishes or desires of any potential newcomers. As has become increasingly apparent, the information needed to make important decisions is always unsatisfactory and incomplete.
Urban areas are so complicated that they are difficult to describe, let alone to plan.
More basically, a great deal of what has motivated plan-makers has been a set of beliefs inherited from positivistic nineteenth century notions in social science about physical determinism and social progress. The remarkable tendency for large scale plans to backfire suggests that this optimism was misplaced. I will argue for a much wider view of planning and the plan. In this view of things, it is important to acknowledge the fact that everyone is planning all of the time. An individual deciding where to buy a piece of clothing or a developer trying to locate a new apartment building does planning just as much as the planning department of a city.