With President Trump and Congress at an impasse over federal spending, the country is in the throes of a partial government shutdown that has shuttered offices and threatens to hold up paychecks during the holiday season and affect popular tourist attractions nationwide.

Here’s a selection of some of the questions people might have.

Q: Has the entire government shut down?

A: Not this time. About three-quarters of the federal budget has been funded through September 2019, which includes the Pentagon, the Department of Veterans Affairs and the Department of Health and Human Services.

Q: So how many federal workers are affected?

This stalemate is just the latest in a long line of threats from President Trump to shut down the government if he doesn't get his way. (Jenny Starrs/The Washington Post)

A: Quite a few. The remaining quarter of the government that lacks funding includes the State, Justice, Treasury, Transportation and Homeland Security departments. All told, about 800,000 of the 2.1 million federal workers nationwide — or more than a third — are affected in some way. If the shutdown continues, nearly half would remain home without pay, while the rest would stay on.

Q: When could people start feeling the impact?

A: That might take a few days. Even though the funding ran out at midnight Friday, that coincided with the beginning of what the federal government views as a four-day holiday weekend. Monday is Christmas Eve, which has been declared a holiday for federal workers, and Tuesday is Christmas Day. So Wednesday is when many of the real effects would begin to hit people.

Q: What about my flight back from the holidays?

A: If you’re one of the tens of millions of people hopping a flight over the next two weeks, don’t worry: Air traffic controllers and federal airline safety inspectors will remain on the job.

Airport security checkpoints will also remain at full staffing, a spokeswoman for the Transportation Safety Administration said, though she added that those workers will not be getting paid. (The assumption is that they will be paid retroactively.) And for those of you taking trains: Amtrak “will continue normal operation” during any short-term shutdown, a spokesman said Friday.

Q: Who else stays on the job?

A: Lots of people, including those patrolling federal prisons, charged with immigration enforcement, issuing weather forecasts and inspecting meat and poultry. The State Department will keep issuing passports and visas, though it has warned that such activities “will remain operational as long as there are sufficient fees to support operations.” The Food and Drug Administration will keep reviewing drugs. Agents with the FBI, Drug Enforcement Administration and Bureau of Alcohol, Tobacco, Firearms and Explosives will keep working, as will the Coast Guard, Border Patrol, Immigration and Customs Enforcement and the National Weather Service’s forecasters, among others.

Q: What stops happening during a shutdown?

A: A grab bag of federal activities. The Internal Revenue Service is closed. At the Federal Communications Commission, calls to consumer complaint hotlines go unanswered. The Small Business Administration is closed. Some facilities could remain open temporarily, while others close their doors.

Q: Do the Smithsonian’s various museums stay open?

A: The Smithsonian museums, including the National Zoo in the District, have leftover funds to stay open through Jan. 1. In its shutdown planning notice, the Smithsonian said that when the available funding is exhausted, “it would be necessary for us to close all museum buildings to the public.” (A word of warning if you’re reading this and planning a visit soon: The Smithsonian’s museums are always closed on Christmas Day.)

Q: What happens to national parks and monuments?

A: They stay open, but don’t expect to find visitor centers actually welcoming visitors. Historic homes and national monuments that shut down at night are closed. If a bunch of snow falls on a park with an area that needs plowing, the snow stays put, the plows stay parked and those spots are inaccessible.

Q: Does the mail keep operating?

A: People sending thank-you cards for holiday gifts are still able to ship those out in the mail during a shutdown. Operations are not affected by a shutdown and all post offices stay open as usual, because the Postal Service funds its operations through its own sales rather than tax dollars.

Q: I’m a federal worker. Am I getting paid?

A: Paychecks for the pay period ending Saturday “should be issued at the normal time (generally, in the December 28 to January 3 time range),” the budget office said in a planning document.

Employees deemed essential, otherwise known as “excepted workers,” who must work during the shutdown, will get paid for that time after the shutdown, according to guidance released by the Office of Personnel Management. For furloughed employees, however, it’s up to Congress whether they get paid for the shutdown period; after every previous shutdown, Congress has passed legislation mandating that furloughed workers be paid.

Q: Do federal workers have to come in even if they’re not supposed to actually work?

A: Some will have to — briefly, anyway. This is what’s known as an “orderly shutdown,” during which employees who are furloughed can be allowed up to come in for up to four hours to preserve their work, finish time cards or turn in their government-issued phones.

A person planning to be away from the office next week does not necessarily have to rush back Wednesday just for the “orderly shutdown” process. The Office of Management and Budget says agencies can let them do that on the first day they were already set to come back.

Q: Hang on. Even when the government shuts down, workers can be expected to come back in just to help shut it down?

A: What can we tell you? The federal government is a quirky enterprise.

Damian Paletta, Ashley Halsey III and Brian Fung contributed to this report.