The statutory limit that the United States Congress places on the amount of debt that the Bureau of the Public Debt can have outstanding at any time. Every few years (and sometimes more than once in a single year), when the debt is about to hit the limit, the Congress raises the limit, with a few members taking the opportunity to say that "we should really do something about the debt".

It used to be the case that Congress would designate an increase in the debt ceiling as permanent or temporary. (There were also extensions, which didn't increase the ceiling, but pushed back the expiration date for a temporary increase.) Temporary ceiling increases can be considered in the same vein as a temporary tax increase, namely, as a fairy tale.

In 1971, the permanent debt ceiling was $400 billion. At the end of 1982, after 19 temporary increases, the permanent limit was still $400 billion dollars, while the debt was $1.197 trillion. Even politicians were starting to see that they couldn't explain that forever, and would have to fix that somehow -- so they discontinued the temporary/permanent distinction.

As of January 31, 2002, the debt ceiling was 5,865,892,000,000 dollars. As of this writing, it has been raised, but I don't have the current figure. (The debt at February 28, 2002 was 6,003,453,016,583 dollars.)