Borrowing on the idea behind the famed greenbelts surrounding English villages, many state and local governments in the U.S. are trying to concentrate growth in some places while sparing others. Glendening has decreed that roads and sewer lines will be provided only in designated areas. The oldest American experiment along these lines is the growth boundary around Portland, Oregon. Since 1979 development has been forbidden outside an area that covers 24 municipalities and three counties. The plan has kept sprawl in check, but competition for limited space has made the city an expensive place to live. Even if governments have the best intentions, growth boundaries are hard to maintain, as has already been found out in Britain, where greenbelts have come under pressure from developers.

PURCHASE LAND

If governments want to protect land, the easiest way is to buy it and take it off the market. New Jersey has issued bonds to raise $1 billion for the preservation of farms and woodlands, and the U.S. Congress mandates the use of $900 million each year to purchase undeveloped land, though it always falls short of allocating the full amount. In Japan activists like Yoshitoshi Era have helped prod local governments to step up land buying. "We have to protect what is left," he says. Private groups and wealthy individuals can open their pocketbooks too. Preservation-minded Doug Tompkins, founder of the Esprit clothing company, has bought 640,000 acres (259,000 hectares) of forest land in Chile.

BUILD MASS TRANSIT

If a city has good rail and bus lines, then development can be concentrated around mass-transit stops rather than spread out all over the countryside. Public transport is still a tough sell in the U.S., but rail lines in most of the world have kept sprawl from being even worse than it is. Says Tony Burton, a member of the Council for the Protection of Rural England: "The dilemma is, if you don't build roads, what do you do? Well, for a start, you prevent sprawl." Curitiba, Brazil, is an up-and-coming city in which an efficient bus system has helped hold down road building.

RESTORE INNER CITIES

In the U.S. especially, development moves out of town while perfectly good urban property is abandoned. Perverse incentives often encourage the trend. Banks deny mortgages in declining neighborhoods, and environmental regulations may make it more expensive for a developer to reclaim an abandoned urban site than to build on virgin land outside the city. But places like Baltimore, Maryland, and Chattanooga, Tennessee, have proved that downtowns can be revived. President Bill Clinton in 1996 signed an Executive Order requiring all new U.S. offices to be placed in urban areas if possible, preferably in historic buildings.

That kind of action makes sense. For decades to come, population growth will put more pressure on our wide-open spaces. So before the human race gobbles up any more land, we could make much better use of what we've already taken.