NEW YORK — As New Yorkers have tussled over the fate of the World Trade Center site these last two years, almost no attention has been paid to a space equal in size to 156 World Trade Center sites: that devoted to public housing. New York City has more public housing units than any other city in the country, by far, with almost 200,000 of the million or so units that exist nationwide covering 2,500 acres of our urban land.

Tenants’ lack of ownership in their apartments and houses and landlords’ lack of incentive to keep up their properties have led to a blight that few dispute is government-created. If members of the Bloomberg administration are looking for a way forward, they could crack open a new volume of essays on housing policy by the director of public policy case studies at Harvard’s John F. Kennedy School of Government, Howard Husock.

Mr. Husock is a contributing editor of the Manhattan Institute’s City Journal, from which the essays in his book, America’s Trillion-Dollar Housing Mistake (Ivan R. Dee, 256 pages, $19.95), are drawn. Mr. Husock paints a devastating portrait of the destruction done by the billions of dollars in subsidies that the government injects into the housing market every year.

Mr. Husock also chronicles the experience of Charlotte, North Carolina, which has applied the key innovation of the 1996 Welfare Reform Act — time limits — to great effect. I spoke to Mr. Husock recently, after reading his book, to discuss ways New York City could apply the lessons of Charlotte.

In his book, Mr. Husock describes Charlotte’s public housing system as “like the new welfare system — short-term aid, provided on the assumption of the recipient’s serious effort to improve her situation.” In most other cities, public housing residents are abandoned to a nearly permanent ghetto. The average stay in public housing is 80 months nationally, according to Mr. Husock, and 99 months in New York City — a little more than eight years.

The nut of the Charlotte experiment is that no one is forced to accept time limits on their public housing, but recipients are offered strong incentives to put an end date on their dependence. To get residents to agree to a time limit of five years, the city offers newer, more desirable housing. Charlotte fulfills its federal mandate to guarantee all low-income residents public housing, but, typically, in rundown, disorderly high-rise projects.

Those who want to move up into nicer, relatively new projects must accept the limits, and show seriousness about improving their situation by working on a high school equivalency certificate or signing up for community-college classes or job-training courses. Between 1995 and 2000, more than 400 residents in the Charlotte “Transitional Family” program have moved out of public housing, and 125 have bought their first homes. These numbers may sound small, but keep in mind that Charlotte is a small city with only about 1,800 non-elderly residents in public housing total.

Mr. Husock, speaking to me last week from Massachusetts, acknowledged that it is no simple task translating a program showing success in a sleepy Southern city to the Big Apple, but he had some ideas on how it could be done. One of the first roadblocks to adopting the Charlotte plan here, according to Mr. Husock, is that New York City isn’t building desirable new housing projects — and it hardly would be a good idea to start adding to our public housing stock in crowded New York.

Instead, he offered, we could give public housing residents an incentive to accept time limits by offering to allow them to keep more of their earnings. Currently, under what is called the Brooke Amendment, public housing residents have to pay a third of their income as rent. If they earn more money, they pay more rent. Offering a fixed lease and allowing residents to keep more of their income in return for promising to pull themselves up by their own bootstraps, could help public housing residents achieve independence.

This would hardly be as radical as things could get. Delaware has instituted a mandatory three-year time limit for all public housing residents. Mr. Husock would also like to see New York City sell public housing complexes to private managers and start tearing them down as the public housing residents move out.

The important thing is to get things moving. Mr. Husock, in his book, decries “freezing” cities in place. East Harlem, he said, with its proximity to Central Park, could be the site of a building boom if only the housing deadlock could be ended. It’s not as sexy as a cultural center or a transportation hub, but it would be about 156 times more important.