Though the savings rate does not account for the increased value of stock and property, or the gains on retirement accounts, many economists still view it as the most useful gauge of the degree to which Americans are making provisions for the future.

For the 34 million households who took money out of their homes over the last four years by refinancing or borrowing against their equity  roughly one-third of the nation  the savings rate was running at a negative 13 percent in the middle of 2006, according to Moody’s Economy.com. That means they were borrowing heavily against their assets to finance their day-to-day lives.

By late last year, the savings rate for this group had improved, but just to negative 7 percent and mostly because tightened standards made loans harder to get.

“For them, that game is over,” said Mark Zandi, chief economist at Economy.com. “They have been spending well beyond their incomes, and now they are seeing the limits of credit.”

Many times before, of course, Americans have found innovative ways to finance spending, even when austerity seemed unavoidable. It could happen again.

The Me Decade was declared dead in the recession of the early 1980s, only to yield to the Age of Greed and later the Internet boom of the 1990s. Over the longer term, the economy should keep growing at a pace that reflects improving productivity and population gains.

But for the first time in decades, credit is especially tight as the bursting of the housing bubble has spread misery across the financial system. In homes now saturated with debt, conspicuous consumption and creative financing have come to seem a sign of excess not unlike that of a suntan in an age of skin cancer.