Economists say there are several ways to measure the national debt. One of the most meaningful ways is to look at the debt held by the public -- the individuals, Wall Street firms and banks around the world that buy bonds sold by the Treasury Department.

• There is currently $3.7 trillion in public debt outstanding -- equal to 45 percent of the economy's total annual output.

• In those terms, the debt peaked at the end of World War II, when it hit 108 percent of gross domestic product.

• Its most recent high was in 1993, after a decade of growing deficits, when it hit 50 percent.

• If all the surpluses projected for the next decade were used for debt reduction, the debt would decline to below 10 percent of GDP by 2009 -- its lowest level since World War I.

"Reducing the federal debt to the public at this stage is unquestionably the most important thing that I believe that we can do if meeting the future needs of the economy is the standard," Federal Reserve Chairman Alan Greenspan said last week.

Yet last year, critics point out, lawmakers from both parties agreed to a budget-busting highway and mass transit bill and to $20 billion in extra spending out of this year's surplus.

Source: Richard W. Stevenson, "The Deficit's Gone, But Not the National Debt," New York Times, January 31, 1999.