Starting Thursday, the US is expected to reach its statutory maximum of $31.381 trillion dollars. The total encompasses all "existing legal obligations, including Social Security and Medicare benefits, military salaries, interest on the national debt, tax refunds, and other payments," according to the Treasury Department.

At that point, Treasury will begin to take what are called "extraordinary measures" to meet obligations without technically falling into default. These are essentially accounting measures — putting off certain contributions to federal employee pension funds to start — that put off the crisis. However, the government's ability to do so would likely run out by sometime in June.

An actual default would be disastrous, not just for the country but the entire global economy. Depending on who is estimating, such a result could cause credit markets to freeze, massive job layoffs, turmoil in international markets, the loss of a preferred reserve currency for the dollar, and plummeting asset values including commercial real estate as international investors who saw the US as a safe haven for their money would become distrustful.