Is US national debt nearing the danger zone?

The numbers are big enough to get the attention of even the most experienced New York Stock Exchange trading specialist or jaded Washington public policy lobbyist: a $192.3 billion federal budget deficit for March and a nearly $1 trillion deficit . . . for just the first six months of fiscal 2009.

That latter total is more than double last year's record $454.8 billion deficit, due to fiscal stimulus and bank bailout spending, the U.S. Treasury Department announced. Although the high total was expected -- the Congressional Budget Office has projected a similar mid-year gap days earlier (pdf) -- the total has alarmed some in public policy and financial circles.