Why has the US government shutdown? What you need to know about the crisis crippling Washington in 2018

Donald Trump's second year as President has begun with the US government closed down thanks to a stalemate in Washington.

Thousands of federal employees have been told not to go to work as Democrats and Republicans blame one another for the crisis.

It is the first time the US government has shut down when one party - in this case the Republicans - has had control of the Congress, Senate and the presidency.

But what does it all mean, and what's it been caused by?

Q. What does a shutdown mean?

A. It means that many non-essential US government functions are suspended and many, but not all, federal employees are told to stay at home. Military operations as well as law enforcement and public safety officials, such as police and air traffic controllers, will carry on working, as will the postal service, which is self-funded.

Elsewhere it’s more hit and miss. The Smithsonian museums and the National Zoo was closing on Monday while some national parks will remain open, at least for now.

Tax audits may stop and visa and passport applications will be delayed but employees who are furloughed should be paid. They’ll just have to wait a little longer for the back pay.

Q. What’s it all about?

A. Immigration. The US government has been operating on temporary funding measures since the end of the fiscal year last September and the latest deadline expired at midnight on Friday.

Republicans and Democrats have been unable to agree on a budget for next year with immigration the main stumbling block. Democrats want any deal tied to a reversal of President Trump’s move to deport about 700,000 so-called Dreamers - undocumented immigrants brought into America as children and allowed to stay under the Obama administration’s Deferred Action for Childhood Arrivals programme.

Republicans want to spend $18 billion (£13 billion) on an immigration crackdown, which would include beefing up border security with the building of Mr Trump’s long-promised wall to stop Mexicans getting into the US illegally. So far neither side will budge.

Q. Is it likely to harm the US economy?

A. A shutdown lasting up to a couple of days will not have a huge impact, but Bloomberg economists estimate that when the government ground to a halt for two and a half weeks in 2013 it subtracted 0.3 per cent from quarterly GDP at a cost of $24 billion to the overall economy.

Q. If the Republicans hold majorities in the House and the Senate, why can’t they just push the budget through?

A. The Republicans don’t have huge majorities. In the 100-member Senate they have just 51 seats. To avoid a filibuster - where one or more senators can speak for as long as they want on anything they choose to block a vote - they need a total of 60 votes

Q. Has this happened in the US before?

A. Yes. There have been 12 shutdowns since 1981, ranging from a single day to 21 days, and under President Jimmy Carter it was a yearly occurrence averaging eleven days each. The most recent one was a 16-day partial shuttering of the government in 2013.

Q. Who will get the blame?

A. A Washington Post-ABC News poll found that 48 percent view President Trump and congressional Republicans as mainly responsible for the situation while 28 percent fault the Democrats.

If the shutdown drags on for long, it could give voters another reason to turn away from incumbents of both parties in a mid-term election.