The Slum, and What Replaced It

The industrial city grew far faster than anybody could house. What filled the gap was the cheapest thing that would let: back-to-back terraces, sharing rear walls so that each dwelling had windows on one side only, with no through-ventilation, no rear access, shared privies and standpipes, and often a family to a room. Britain prohibited new construction of it in 1909, and the last of it was occupied into the 1970s.

It is tempting to call this a market failure. It was not: it was what a functioning market produced at that wage and that land price. Builders built the cheapest thing that would let and tenants took it because the alternative was nothing at all. That distinction matters, because it identifies what actually fixed it. Not competition (competition produced it) but regulation, subsidy and higher wages, each fought over for decades.

Building codes came first, and they contain the tension that has never been resolved. Minimum ceiling heights, window areas, drainage, spacing between rows: every one of them improves the housing that gets built and reduces how much gets built, because every one of them costs money and money appears in rent or in fewer units. That is not an argument against codes. The housing they outlawed was killing children. It is the reason the argument recurs in every generation, currently under the heading of whether standards price people out of housing, with both sides holding a real point.

Then came clearance, which is where the twentieth century made its characteristic mistake. Whole districts were demolished and their occupants rehoused, usually in far fewer units and usually somewhere else. The buildings were genuinely bad. What went with them was not visible on any survey of housing conditions: the dense street layout that supported cheap premises for a man mending shoes in a front room, the informal childcare of a neighbour two doors down, the casual work found by word of mouth, and the simple fact of being overlooked by people who noticed things.

Jane Jacobs' objection was functional rather than aesthetic, which is why it has aged so well. Her argument was that old, dense, mixed streets generate safety and opportunity as by-products of their layout (eyes on the street, short blocks, buildings of different ages and therefore different rents) and that a plan drawn at a distance optimises what is visible at a distance. Light, air and open space are visible. Everything else is deleted silently.

The result, in a great many cities, was better dwellings inside worse places to live, and a set of problems that nobody had predicted because nobody had been measuring the thing that was destroyed.

None of which resolves the underlying trade, and it is worth being honest that it does not. Without standards you get back-to-backs. With standards set high enough you get fewer homes and higher rents for everybody outside them. What the history offers is not an answer but the correct question, which has to be asked at each income level rather than once: what is the minimum worth insisting on, and who bears the cost of the housing that therefore does not get built?