For the past few years, there have been many close calls regarding the U.S national debt.

In 2011, the U.S nearly defaulted on its debt. This led the S&P500 rating to drop from AAA to AA+. Imagine yourself borrowing some money from someone, and later on tell them that you cannot pay them back. That person will then trust you less the next time you need to borrow money.

In 2012, the U.S government was shut down for two weeks because they ran out of money.

The national debt is built up by budget deficit, which occurs when the government spends more money than it collects from taxes and other stuff.

As of right now, the U.S national debt is around 18 trillion dollars. About half of the national debt is held by the government, lying in Treasuries held by feds and other intergovernmental agencies; the majority of the rest is foreign debt and others, such as pension funds, mutual funds, depository institution, and so on.

The national debt is expected to go up by 9 trillion dollars in the next 8 years (next two presidential terms).

Here's one of my favorite toy to check out the debt.

It shows you about the change in national debt, and tons of other stuff such as national GDP, budget deficit, the monetary base, price of gold, the auto industry, etc.