People pass in front of the National Archives, one of the agencies at risk of a partial shutdown.

As lawmakers scrambled to avert a midnight government shutdown, federal agencies lumbered into action on Friday, laying last-minute plans for how best to do nothing - or as little as necessary.

Across the vast bureaucracy, from custodians who clean buildings to the people who maintain the nuclear-weapons stockpile, federal employees sought to figure out whether they will be paid and whether they will fall into the category of "excepted" workers who would be expected to show up no matter how long the impasse lasts between Congress and President Donald Trump.

Late Friday night, White House budget director Mick Mulvaney officially notified federal agencies to begin the shutdown at midnight.

There was plenty of confusion throughout the day.

New York state officials reached an agreement late Friday to pay the National Park Service to keep the Statue of Liberty open to visitors during the final days of December, a person briefed on the discussions said, an effort to backstop local businesses and thousands of tourists.

A portrait of President Donald Trump is displayed at the entrance of the Environmental Protection Agency.

At the White House Visitor Center, where people went looking for holiday stocking stuffers, workers manning the entrance were asked whether they knew what would happen to work schedules. "We'll find out at midnight," one said, shrugging wanly.

Friday morning at the Commerce Department, things weren't much clearer. Commerce Secretary Wilbur Ross sent an email to employees Friday morning declaring that the agency was still "working to update our contingency plans for executing an orderly shutdown of activities."

With the pay period ending Dec. 22, federal workers will receive their next paycheck, but it will be up to Congress and the president about how to compensate people for the pay period starting next week if the shutdown lasts that long.

All told, about 800,000 of 2.1 million federal workers nationwide - or more than a third - would be affected in some way. Nearly half would be sent home without pay.

Many of those left wondering about their paychecks are part of an estimated 3.7 million people who are contract workers, including those at big consulting firms such as Deloitte, and approximately 2,000 janitors, security guards and other federal building workers who work for independent contractors.

Lila Johnson, 71, has worked as a cleaner at the State Department for two decades, sweeping floors and scrubbing bathrooms for $21 an hour. Now she's worried about making her rent, car and life insurance payments, she said.

"It's Christmastime," Johnson said. "People need their money."

Government shutdowns have happened periodically since a series of one-day closures in the 1980s and the three-day Columbus Day weekend closure in 1990, when the late President George H.W. Bush was reluctant to agree to higher taxes after campaigning on the slogan of "no new taxes."

In 1996, a dispute between President Bill Clinton and Congress kept nonessential services closed for 27 days. In 2013, a spat between President Barack Obama and Congress kept the government closed for 16 days.

If budget talks fail this weekend, the government would shut down for the third time this year.

"It seems to me that the president has wanted to close the government since he took office," said Douglas Holtz-Eakin, president of the American Action Forum and former head of the Congressional Budget Office and the Council of Economic Advisers under President George H.W. Bush. "It's clear he sees this as a political winner. Traditionally that's not true."

To some federal workers, government shutdowns have become routine.

Dan Wenk, who retired from his post as Yellowstone National Park superintendent at the end of September, said officials at the park plan for what to do if federal funding lapses.

"This is something we do every year, plan for a shutdown," Wenk said in phone interview. "It's standard operating procedure. Isn't that sad?"

Park officials have begun discussions with people who run concessions, who are permitted to defray the costs of operations during a shutdown, such as grooming the roads. But even if they do that, Wenk said, smaller concessionaries such as snowmobile and ski-rental operators will take a financial hit that they cannot offset easily.

"Their rates have been approved," he said. "They can't raise their rates, they just cut into their margins."

The Office of Management and Budget issued guidelines assuring workers that if paychecks are suspended, then furlough days would not also count as vacation days. And while OMB urged agencies to spend four hours with each employee going over "orderly shutdown" procedures, people did not have to return from vacation next Wednesday for that, the agency said.

The World War II Memorial would be open during this federal government shutdown, unlike when it was closed during the 2013 shutdown.

Despite OMB's densely written guidance, there was still confusion over whether employees at some agencies would have to show up next Wednesday or give up their laptops and cellphones. Notifying employees was a confusing task: How can you contact people at their government-issued email address when they are on vacation - and, by law, not allowed to be working?

"Shutdowns tend to be very disorganized," said Tony Reardon, president of the National Treasury Employees Union, which represents IRS employees and many others who will be affected. "But it seems to me that this time it's been made even worse."

Even though many workers would be away from their offices over the holidays anyway, many experts say a shutdown, especially a prolonged one, would disrupt many essential services.

The Internal Revenue Service's contingency plan says approximately 70,000 employees could be furloughed during a shutdown in December. That number - approximately 88 percent of the IRS workforce - is high because taxpayer filing season has not started.

But thousands of IRS employees are currently being trained to provide advice about complicated new changes to the tax code when taxpayers begin filing mid-January.

"A short shutdown really has about no effect, if it's a day or two," said Mark Mazur, who served as assistant secretary for tax policy at Treasury and now works the Tax Policy Center, a nonpartisan think tank. "A weeks-long shutdown means that for things that need to get done for the filing season, there may not be the people there to do them."

Large numbers of federal workers would remain on the job, however, even though they would not get paid until the budget impasse is over.

If the agencies close at midnight, it will not be noticeable to most Americans, since most federal offices will be closed anyway. Border Patrol agents will still be on patrol for middle-of-the-night border crossers and on duty at ports of entry. Air traffic controllers will still be on overnight shifts. Meat inspectors who work the midnight shift will report to work. So will wildland firefighters.

At the Justice Department, roughly 80 percent to 84 percent have been deemed essential, in large part because the Bureau of Prisons must keep running, and because of public safety and national security dimensions of the Federal Bureau of Investigations and other Justice officials.

"In the civil arena, typically attorneys with filing obligations that cannot be rescheduled will be allowed to meet court deadlines for filings [and] appearances," the department said in a statement.

Even though employees deemed "essential" will be paid when the shutdown ends, the delay will squeeze those who are relatively low-paid, like Forest Service firefighters.

"Many of these are seasonal employees living close to the poverty line," said Randy Erwin, national president of the National Federation of Federal Employees, which represents about 30,000 of those who will be affected by the shutdown. "These are people who cannot just float a no-interest loan to the government."

Some agencies have their own income streams. The government-owned Tennessee Valley Authority, which provides electricity to 10 million people in seven states, will not be affected.

In the event of a U.S. federal government shutdown, the Smithsonian can use prior-year funds to remain open to the public. All Smithsonian museums and the National Zoo will remain open at least through Jan. 1. Smithsonian museums are always closed Dec. 25.

People sending thank you cards for holiday gifts will still be able to ship those out in the mail. U.S. Postal Service operations would not be affected by a shutdown, and all post offices would stay open as usual, a spokeswoman said in a statement, because the U.S. Postal Service is "an independent entity that is funded through the sale of our products and services, and not by tax dollars."

Some government workers refused to let the budget impasse spoil their Christmas cheer. In the event of a government shutdown, the North American Aerospace Defense Command, an essential agency, said it would continue its 63-year tradition of tracking Santa Claus on a sleigh. Military personnel who conduct NORAD Tracks Santa are supported by approximately 1,500 volunteers who answer phone calls about Santa's whereabouts.