Consumerism is as American as cherry pie. Plasma TVs, iPods, granite countertops: you name it, we’ll buy it. To finance the national pastime, Americans have been borrowing from abroad on an increasingly stunning scale. In 2006, the infusion of foreign cash required to close the gap between American incomes and consumption reached nearly 7 percent of gross domestic product (GDP), leaving the United States with a deficit in its current account (an annual measure of capital flows to and from the rest of the world) of more than $850 billion. In other words, the quantity of goods and services that Americans consumed last year in excess of what we produced was close to the entire annual output of Brazil. “Brazil is the tenth largest economy on the planet,” points out Laura Alfaro, an associate professor of business administration who teaches a class on the current account deficit at Harvard Business School (HBS). “That is what the U.S. is eating up every year—a Brazil or a Mexico.”

Whether this practice is sustainable—and if not, how it might end—are questions that divide scholars and investors alike. We have borrowed so much from abroad—between half a trillion and a trillion dollars a year for the past six or seven years—that in 2006, our investment balance with the rest of the world (what we pay foreign investors on their U.S. assets versus their payments to us on our investments abroad, historically nearly equal) tipped to became an outflow for the first time in more than 50 years. We are a debtor nation swiftly heading deeper into debt.

How America's addiction to consumerism has left us debt-ridden, on the level of both citizen and nation, with all signs pointing to things getting worse.

“Part of the reason people are spending beyond their means,” says Rawi Abdelal, an associate professor of business administration at HBS, “is because they are—in a way—witnessing the end of the American dream.” Between 2000 and 2005, even as the U.S. economy grew 14 percent in real terms, and worker productivity increased a remarkable 16.6 percent, workers’ average hourly wages were stagnant. The median family income fell 2.9 percent.