Here are 5 things that happen in a government shutdown

Then-White House Chief Strategist Steve Bannon listens as President Donald Trump speaks during a meeting on cyber security in the Roosevelt Room of the White House in Washington Tuesday Jan. 31 2017

When the government shut down for 16 days in October 2013, employees were retroactively paid when a deal was made to fund the government.

Budget Director Mick Mulvaney Friday morning put the chances of a shutdown at "between 50 and 60 percent". "We're not going to weaponize it", he said.

Officials of the Customs and Border Patrol, Immigration and Customs Enforcement, and US Citizenship and Immigration Services will remain on the job checking and processing people entering the country by land, sea and air. The Social Security Administration and Medicare also are regarded as critical agencies that would not close their doors in a shutdown, so those benefits should not be interrupted.

"All military personnel performing active duty will continue in a normal duty status", the Pentagon ordered Thursday. But FEMA itself doesn't remain totally operating during a shutdown; more than 3,000 of FEMA's employees would be suspended, according to the Homeland Security Department's plans for a government shutdown.

Spokesman Eric Durr said during a shutdown there would be no Guard drills and training and soldiers would not attend training schools they would have normally attended.

Even the military is affected.

If Congress doesn't manage to pass a spending bill by midnight on January 19, the United States could be headed for the first government shutdown of the Trump administration.

As a result, he added "it's too early to say" whether a shutdown could have an effect on the roll out of the legislation.

Will the Federal Emergency Management Agency stay open to continue supporting recovery in California, Florida, Puerto Rico, and Texas?

Military operations, air traffic control, medical care of veterans and federal criminal investigations - including a certain probe of the president's inner circle - are among the essential activities that will go on. The shutdown lasted for 16 days, triggered by a disagreement over Obamacare.

The Department of Veterans Affairs has a special line of funding that will keep all of its hospitals open and nearly all of its medical employees on duty.

"Other areas such as culturally sensitive areas or backcountry areas that present a risk to visitors may also have restricted access". And what about the National Parks, monuments, and Smithsonian museums? All animals would be continued to be fed, but, in a setback for panda lovers, the zoo's popular Panda Cam and other live animal cameras would not be broadcasting. For instance, all national parks are closed and Medicare can not accept new applicants. For example, contract shutdown costs and startup costs once the shutdown is over, the costs of stopped or terminated subcontracts, or even the increased costs of performing contracts not stopped or terminated by the shutdown.

According to its contingency plan, the Justice Department, with almost 115,000 employees, has a "high percentage" of employees who would be able to keep working because they have national security, law enforcement and criminal justice system responsibilities relating to safety or protection of property.

Thanks to a Reagan-era memorandum, federal workers involved in national security-related work, or performing jobs that "protect life and property" will still report to work. The State Department's passport services are funded partly by fees, which means it is not completely dependent on Congress for money and may be able to continue to issue passports for at least a short time.

Additionally, these employees are not technically entitled to back pay to make up for the work they are forced to miss. It will be up to Congress to approve retroactive pay later.

Will the NTSB (National Transportation Safety Board) keep working?

But what is considered essential and nonessential? The federal appeals court would still hold arguments and accept filings, though some employees might be furloughed. Such temporary layoffs are supposed to be for non-essential personnel, but as much as two-thirds of the CDC's employees might be unable to work during the height of the current flu epidemic.

Yes, many of them - but they might not get paid for a while. And hundreds of thousands of federal workers would begin to be furloughed until a funding agreement is reached with no guarantee of restoring their lost pay.