The Total US Public Debt stood at around $31.46 Trillion as of Feb 10th this year according to a report by PEW Research Center. While the public holds most of this debt about one-fifth are owned by another arm of the government itself.

The following chart shows the growth of the total US debt over the years:

Click to enlarge

Source: The US debt ceiling, commodity supercycles, & oil, Market Index

The educational piece at the Market Index above link provides a good overview for understanding the debt ceiling.

Here is a fascinating excerpt:

Lessons from History

Since 1960, Congress has permanently raised, temporarily extended, or revised the definition of the debt limit 78 times, according to the US Treasury Department. 

49 instances occurred under Republican presidents.

29 instances occurred under Democratic presidents. 

Yep – the debt ceiling is revised (on average) 1.23 times a year. 

Related:

• 5 facts about the U.S. national debt, PEW Research Center