Sam Smith, Utne Reader, 2000 - Not everyone who leaves the city wants to. In a large number of cases, the cost and availability of housing provides the impetus. Among the factors that have raised the cost and lowered the availability has been gentrification. The gentrifiers not only upscaled the housing stock, they have reduced it, since they require more space per-capita in which to live than did former residents.
One of the simplest, cheapest and quickest ways to counteract this trend is to permit accessory apartments (sometimes called granny flats) in single-family zones. Many of these apartments exist illegally -- there are an estimated 40,000 in LA alone -- supporting my theory that one of the best places to look for good ideas is in the underground economy. If normally law-abiding people insist on doing something against the rules, there's a good chance that the people know something the law doesn't.
The advantages of such apartments include lowering the effective cost of housing for the homeowner, increasing the supply of housing, providing a social and economic mix within neighborhoods, allowing voluntary individual care to replace some of the need for social services (e.g. the young apartment dweller helping the aged landlord upstairs), providing neighborhood-based economic opportunity and increasing the number of eyes on the street.
Reviving the practice of taking in boarders could also greatly improve the availability of housing. The boarder tradition played a major role in the growth of the American city, proving newcomers with an inexpensive place to stay and adding a source of income to those who had lived in the city long enough to own a house.
A more radical approach is co-housing. Co-housing involves individual homes clustered around a large common house with such facilities as a dining room, children's playroom, workshops and laundries. The houses typically have their own kitchen and are otherwise minimally self-sufficient but with the emphasis on communal facilities. Each co-housing plan is worked out with intense participation by future occupants. There is no single plan for these projects; they are designed for specific and changing needs and hospitable to spontaneity., The co-housing approach has been used for condominiums, cooperatives and non-profit rental housing.
There are other things to do. We could encourage the construction of more two and three family homes that were once a staple of urban America. We could build "grow houses" such as the 575-square foot designs of New Haven architect Melanie Taylor that are being built for as little as $30,000 in the southeastern US. Even more novel are the modular homes designed to grow or deconstruct over time as required by the occupants' changing lifestyle. The design of the Center for Maximum Building Tecnologies in Austin, Tex., allows for modules to be detached and moved to another house when the current owner no longer needs them.