What the U.S. National Debt Is:
The rest is owed by the government to itself, and is held as Government Account securities. Most of this is owed to Social Security and other trust funds, which were running surpluses. These securities are a promise to repay these funds when Baby Boomers retire over the next 20 years. (Source: U.S. Treasury, Debt to the Penny; Debt FAQ)
The Size of the U.S. Debt:
Even before the economic crisis, the U.S. debt grew 50% between 2000-2007, ballooning from $6-$9 trillion. The $700 billion bailout helped the debt grow to $10.5 trillion by December 2008. The debt is tracked by the national debt clock.
The U.S. Debt Level:
Interest on the debt was $454 billion in Fiscal Year 2011, the highest ever. That's despite lower interest rates. The interest on the debt is the fifth largest Federal budget item, after Defense and Security spending ($890 billion), Social Security ($730 billion) and Medicare ($490 billion). (Source: U.S. Treasury, Interest)
How Did the Debt Get So Large?:
In the short run, the economy and voters benefited from deficit spending. Usually, however, holders of the debt want larger interest payments to compensate for what they perceive as an increasing risk that they won't be repaid. This added interest payment expense usually forces a government to keep debt within reasonable limits.
The U.S. also has a debt ceiling, which attempts to limit the debt. However, Congress usually raises the ceiling to prevent the negative consequences of a debt default.
Second, foreign countries increased their holdings of Treasury Bonds as a safe haven, also keeping interest rates low. These holdings went from 13% in 1988 to 31% in 2011. During the recession, countries like China and Japan increased their holdings of Treasuries to keep their currencies low relative to the dollar. Even though China warns the U.S. to lower its debt, it keeps buying more Treasuries. For more, see How China Affects the U.S. Economy.
Of the total foreign holdings ($4.49 trillion), China owns $1.1 trillion and Japan owns $900 billion. The U.K. owns $300 billion, while Brazil, the oil exporting countries, Hong Kong, Russia and Canada own between $100-$280 billion each. The Bureau of International Settlements suspects that much of the holdings by Belgium, Caribbean Banking Centers and Luxembourg are fronts for more oil-exporting countries, or hedge funds, that do not wish to be identified. (Source: Foreign Holding of U.S. Treasury Securities, April 2011; U.S. Treasury report ”Petrodollars and Global Imbalances”, February 2006)
How The U.S. Debt Affects the Economy:
The bottom line is that the large Federal debt is like driving with the emergency brake on, further slowing the U.S. economy.


