A picture says a thousand words. From the NYT today:
In particular, who racked up $6.1 trillion in debt?
For more graphs, see here and here.
Update 9:20am 7/29: Reader CoRev excoriates me for using a graphic along FY lines (well a lot of spending is baked in, so Presidents usually are more responsible for the FYs that the NY Times allocated). Well, since we have a set of magical instruments called the Internet, and Excel, we can easily see that there is little change using quarterly data, and timing the cumulations more tightly.
Figure 0: Cumulative changes in publicly held debt, by Presidential administrations, in millions of $, NSA. Source: Treasury via FREDII (series FYGFDPUN), and directly from Treasury for 2011Q1.
I don't see a drastic revision to the stylized facts. Here is a corresponding graph normalized by GDP, which is more relevant.
Figure 1: Cumulative changes in publicly held debt, by Presidential administrations, in millions of $, NSA, normalized by GDP, in billions of $, SAAR, all through 2011Q1. Source: Treasury via FREDII (series FYGFDPUN), Band directly from Treasury for 2011Q1, BEA 2011Q2 advance release, and author's calculations.
Note that in this last graph, the "Clinton" block is below the zero line because publicly held debt was paid down during the Clinton Administration, in ppts of GDP terms. If we normalized by potential nominal GDP, the Obama block would look smaller. I also find of interest the debt accumulated during Reagan, GHW Bush, and Bush Administrations versus that during Clinton and Obama... (recalling Clinton paid down, as a share of GDP).