In July 1893, 115 years ago, the historian Frederick Jackson Turner told an academic symposium that the American frontier was closed - a shocking notion for a people who'd defined themselves by their steady expansion across the continent. This spring, something just as profound and defining has happened: Pulled back by the inescapable gravity of higher prices and the growing scarcity of fossil fuels, we're starting a slow recoil into more dense and compact regions and localities. The frontier of endless mobility that we've known our entire lives is closing.
For the first time in decades, the average number of vehicle miles driven by Americans is falling, down 1 percent for the year and more than 6 percent in May alone. The percentage of Americans planning a driving vacation in the next six months is at an all-time low.
The airlines are fighting hard to contract, slashing the number of planes they fly and the number of routes they serve. United was supposed to begin service this month between San Francisco and Guangzhou, China, but just announced it would take a pass, at least for now. This summer's flights to Hawaii will carry 13 percent fewer passengers.
As the rising price of fuel makes it harder to truck and fly food around the globe, and as the search for more energy from sources such as ethanol contributes to higher food prices, new gardeners are sprouting up. Burpee Seeds, the nation's largest seed company, reported that its sales doubled this spring compared with last year; Seed Savers Exchange sold more packets in the first third of this year than in all of 2007. One grower reported buyers asking questions such as "Tomatoes are a plant?" Indeed they are, and in the future we will grow more of them. Less than 1 percent of America now farms, but local farmers markets are the fastest growing part of the food economy, and in many areas the number of small farms is on the rise for the first time in a century.
One might argue that this is a momentary blip - that soon the price of oil will fall or we'll discover some easy substitute and resume our steady expansion. But even if we're living through a temporary super-spike in petroleum prices, the trend is clearly toward scarcity. And replacement fuels, such as those from the sun and the wind, are by their nature better suited for dispersed, local use. Think about the kind of long-term investments people are making: You can't find buyers for the big pile with the three-car garage at the outer fringe of suburbia, but small and close-in homes are holding their value. One recent Texas study found that a house is worth $4,700 more for each minute it saves in commuting.
For the moment, watching gas prices roll relentlessly higher, we're transfixed by the slightly terrifying novelty of it all. But it won't take long for these changes to become permanent realities. This shift will change our sense of identity and expectation more than anything that's happened in decades.
We could debate whether those changes will be good or bad. I think, on balance, that they're positive - that in the United States sprawl has eroded our sense of community, with grievous results. (Almost every index shows that the less far-flung Europeans are happier.) Overseas, more and more experts argue that export-driven hyperdevelopment is turning into a recipe for ecological disaster and social dislocation.
Still, there's no question this change comes at a cost; there was something lovely about the dream of a seamless world. Which is why it's good that there's one major countervailing trend: the rise of the Internet and, with it, the ease of vital communication. This month, for instance, a few of us launched an international grass-roots campaign to address that most stubborn of planetary problems, global warming. We're calling it 350.org - the number, measured in parts per million, that scientists say is the most carbon dioxide we can safely harbor in the atmosphere. It may be the most important number on Earth, and the Internet was invented, in some sense, to spread it around the globe. Already we've heard from artists, musicians and activists dramatizing those digits in Congo, Sweden, Nepal, each of them trying to put pressure on international negotiators to forge a powerful global treaty.
We can still share the Earth, in other words. But recipes, not ingredients. Ideas, not cargo containers. From the keyboard, not the driver's seat.
Bill McKibben is a scholar in residence at Middlebury College and the author of "Deep Economy: The Wealth of Communities and the Durable Future."