The crash Oct. 29, 1929

Others say the Crash was an important blow to consumer confidence but dismiss the cause-and-effect argument. In the 1980s, the young Princeton economist Ben S. Bernanke made a persuasive case that an ordinary recession turned into the Great Depression only after the Federal Reserve and the Hoover administration failed to contain a series of unrelated events in late 1930 and early 1931. Bernanke today is chairman of the Fed, the institution leading international rescue efforts in the current crisis.

"The first point to be made is that the Depression was underway even before the Crash," says Robert S. McElvaine, author of "The Great Depression: America, 1929-1941."

The economy began to unravel in the summer of 1929, he says, as lending began to dry up and industrial production fell. Farm incomes had been badly battered throughout the 1920s, and took another hit with the onset of a prolonged drought in the Midwest starting about 1930.

Contrary to the depiction of Okies and Arkies fleeing to California in John Steinbeck's "The Grapes of Wrath," however, rural migration slowed during the 1930s, says McElvaine. "If you could stay on the farm, you did," he says. (In fact, many of those heading West weren't refugees from the Dust Bowl at all. The drought mostly affected farmers in Kansas, Texas, New Mexico, Colorado and a portion of Oklahoma.)

Perhaps even worse, by the late 1920s, consumers could no longer afford to buy what manufacturers were turning out, Kyvig says.

Wages had risen slowly during the decade, but consumption had grown much faster thanks to the widespread introduction of installment-plan financing, he says. Consumer items such as household appliances and radios, which banks once had been reluctant to finance (because the collateral could easily be spirited away), were now regularly being sold on credit offered by manufacturers and merchants.

Radio advertising and other new mass advertising techniques broke down traditional ideas about indebtedness, Kyvig says. Even the language changed, as advertisers told customers they were offering "credit," a much more seductive concept than a "loan."

The result is familiar to us now: People stretched themselves to their limits and beyond. By 1930, the consumer credit boom had run its course. Soon, inventories of unsold goods began to pile up, and companies started cutting production. That fed a downward cycle of job losses and manufacturing cuts.

President Herbert Hoover, who had been a successful businessman, tried to put the best face on the deteriorating conditions. In 1930 he began to refer to the economic decline as a "depression," a word that hadn't yet acquired its frightening connotation, McElvaine says. Depression suggested a slight dip and sounded less severe than "panic" or "crisis," two words that had been used to describe earlier economic breakdowns, he says.

Washington only seemed to make things worse, historians say. Rather than stimulating the economy with tax rebates and deficit spending -- two responses in our present crises -- Congress and President Hoover agreed to raise taxes to balance the federal budget. The Federal Reserve, meanwhile, tightened interest rates, starving the economy of money and deepening the economy's trouble.

Says Klingaman: "The image that stuck in my mind is when a snowstorm turns into a blizzard. The snow just keeps falling and piling up. You look out your window and you say, 'Oh, my God, it isn't stopping.' The bad news was like that. It just kept piling up."