When he starts a column with the phrase “underneath the apparent stability of the Great Moderation lurked a rapid rise in debt that is now being unwound”, and uses this graph as evidence

debt as % of GDP. Shows a rise from before 1990, with a kink upward at around 2000Q4, then a decline when the recession ended.

, then someone who is as much of a fan of FRED as I am is going to want to reproduce Krugman’s data, whence we end up with

Same graph as above, but on a longer time scale. Basically debt as a % of GDP increased continuously from the early 1950s until the recession.

I’ll grant that something especially crazy started happening around the year 2000, but I don’t think you’d really single out that particular era, if this graph were your only bit of evidence, and say, “Ah ha! Debt really became unsustainably large right *there!*” Debt has been increasing continuously since the 1950s. The point of Krugman’s article lies in other directions (namely, how much of a hit on future GDP we’ll take because the country is now deleveraging), but my question would be: how far do we have to fall? Back to where it was in 1999? Or back to where it was in 1960?