When it comes to urging environment-mindedness, high oil prices have proven much more persuasive than green groups ever did. The U.S. economy, built on cheap, plentiful energy, is shifting into a new mode. Americans are driving less, riding transit more, ditching SUVs, and moving back into city centers. We’re seeking energy efficiency in our appliances and our heating, cooling, and lighting. Solar energy is having its day in the sun. Companies are rethinking their global supply chains, and consumers too are seeing the benefits of staying close to home. “The environmentalists have always asked you to eat locally,” says economist Matthew Kahn. “But now the businessmen will agree.” The adjustment carries growing shrinking pains: layoffs, high food prices, and overwhelmed infrastructure, to name just a few. But many economists suspect that the era of cheap fuel has officially come to an end; it remains to be seen whether the American economy can run as well — or better — on efficiency as it did on profligacy.