The Statue of Liberty is not accepting huddled masses at this time, but the beleaguered U.S. Post Office is still processing packages and delivering mail after lawmakers failed to pass a spending bill on Friday, sending the federal government into shutdown limbo.

After the federal spending authority expired at midnight Saturday, federal workers deemed "non-essential" were furloughed, a temporary layoff. “Essential” federal workers are still on the job. Airports, national mail service, national security and law enforcement operations, among others, are still operating.

Most federal buildings are closed, but some are still operating with non-furloughed employees, they’re just not open to the public.

But there are some noticeable differences between this shutdown and the last shutdown, which took place in 2013.

Mick Mulvaney, the director of the Office of Management and Budget, said this shutdown will be different because agencies will be encouraged to use available funds to keep parts of the government operating. He said the most recent shutdown, in 2013 during the Obama administration, was "weaponized" to achieve maximum disruption.

"We're not going to weaponize it," he told reporters at a briefing on Friday.

This time, for instance, Americans will still be able to visit the country's national parks and landmarks. During the 2013 shutdown, the Department of Interior concluded that keeping parks open was not essential. The Trump administration is taking a different stance.

There is no federal law that automatically determines what stays and what goes during a shutdown. In general, operations of the government cease because the money runs out, but there are exceptions.

Who's working and what's open?

FBI agents, Transportation Security Administration screeners at the nation's airports and the Coast Guard are still on the job. Meat and poultry inspectors, air traffic controllers and members of Congress, excluding their staffs, are also still working — and likely many are scrambling to find a solution to funding the government.

Most federal employees, which includes staff at the Centers for Disease Control, who are dealing with the flu epidemic, and staff at the Internal Revenue Service, who are dealing with the new tax law and in the beginning stages of processing tax returns, remain on the job. So do rangers at national parks.

U.S. Customs and Border Protection agents are also on the job.

The Smithsonian Institution’s museums, the National Zoo, Veteran Affairs hospitals, federal courts and the U.S. Postal Service are open.

Social security checks, Supplemental Security Income, unemployment pay, Temporary Assistance for Needy Families, food stamps and medicaid benefits will still be received by recipients because they're not paid from annual appropriations by Congress.

Federal prisons are still operating. Also, Robert Mueller's special counsel investigation, which is funded directly by Congress, not through the Department of Justice, will still be funded.

Who stays home and what's closed?

The National Park Service said in a statement that The Statue of Liberty National Monument and Ellis Island are closed due to the shutdown.

The Department of Health and Human Services issued a memo that would furlough 50 percent of its staff and cut back certain services, such as Indian Health Services and child welfare programs. It continues treating current patients, however.

The Department of Defense also issued guidance saying military and civilian personnel will continue normal duty but would not be paid. Military death benefits will not be dispersed.

The Department of Education said in a memo more that 90 percent of its total staff for the first week would be sent home, but federal financial aid workers would still work.