The U.S. economy is afloat today thanks only to the undaunted American consumer. Breaking the pattern seen in other downturns of the past half century, consumption grew at a brisk pace through the three quarters of recession in 2001. Despite plunging stock prices, the spending binge continued last year, financed by record borrowing, a huge wave of mortgage refinancing and home-equity loans, a large federal tax cut, and anemic household saving. Were it not for the persistence of American shoppers, the economy would surely have headed into a tailspin.