The subdivision is the dominant building typology of contemporary urbanism. The prototype subdivision was Levittown, Long Island New York State. Built for soldiers returning from the war, it served the role of emergency housing in a crowded post-war. In that sense, the mass-produced uniform housing estate had a useful purpose.
Today the Levittown has evolved into the Planned Unit Development, a system of private community ownership where a Homeowners’ Association controls a covenant on individual houses. It is, in essence, a condominium of freestanding houses. As a single-design, strictly planned, high-capital project, the subdivision contradicts the basic purpose of cities, to allow complexity with randomly-connected differentiated fragments. Houses in a subdivision are identical and, should they have a reason to form relationships with each other, are part of a public space network that is intentionally disconnective.
The outcome of this is that subdivisions will form relationships only outside of themselves, over large-scale networks. That makes them not fractal to begin with, and because the master plan must be conformed to, prevents them from becoming fractal while growing into a true city. And so it is obvious that the basic atomic element of the modern city is not the single-family house, as it was for most of history, but the subdivision of single-family houses.
For most of history, the growth of cities was a painstakingly slow process of accretion of small buildings. The idea of a subdivision would have been ridiculous, for there would never be enough newcomers to a city to justify producing such large developments. It wasn’t until an artificially-induced housing crisis, the return of WWII draftees from the war, that subdivision-building became economically possible. My belief is that dominance of subdivisions in all form of urban growth today, especially in rural regions, involves a permanent state of housing crisis. Because cities have abdicated their fundamental economic roles, the production of streets and public space networks, random growth can only happen at the scale of the subdivision. And so this why, when we zoom out of the satellite picture of Phoenix, we observe random growth, but when we zoom in at the level of a single square, we see subdivision after subdivision over a monotonous grid of “arterial” highways.
The planning system used by the cities of Phoenix is essentially that which was used by 1811 Plan of New York. The city provides a uniform matrix of blocks that the “market” (subdivision builders) fill in with random stuff. Only now the blocks are gigantic (1 mile by 1 mile across, the size of the whole City of London), and some have at most 3 different kinds of buildings in them. Since buildings and site plans must be approved by the planning agencies, despite the fact that they no longer actually produce any of the public space, the small builder is at an enormous competitive disadvantage.
The City Planners have created a permanent housing crisis by imposing regulatory processes such that very small building projects are impossible to conduct, which is what has made the large building projects, subdivisions, financially viable even in areas where there is no city.
The greatest irony about subdivisions is that they do not represent unlimited economic growth, they can only appear when small growth has been suppressed and the urban network cannot maintain its balance by small transformations.