How have financial markets reacted to news of the shutdown?
US markets were closed by the time the formal notices started going out late on Monday night ordering government agencies to suspend their activities – the so-called shutdown.
But on international markets overnight and on Tuesday morning, the dollar has lost around half a percent of its value, pushing the pound up to $1.6238 – the highest level since 3 January 2013. The euro has risen to $1.357, the highest level since early February.
However, international stock markets were largely unmoved by the crisis – French and German shares, for example, were up around 0.5% – with most investors expecting the shutdown to be short-lived, and the impact largely confined to the US.
Some analysts said investors may also be reasoning that the crisis could delay the so-called "tapering" of the Federal Reserve's recession-busting policy of quantitative easing, which helps inflate share prices by pumping cheap money into financial markets.
Ilya Spivak, currency strategist at Daily FX, said: "The somewhat counter-intuitive response seems to reflect investors' continued pre-occupation with the direction of US monetary policy. Filtered through this prism, the shutdown and its negative implications for US growth are seen as delaying a move to 'taper' QE asset purchases, which seems to be driving a swell in risk appetite."
So does that mean it's just a little local difficulty for the Americans?