With Christmas and Hanukkah just days away, millions of Americans are packing their bags and preparing to hit the road. Meanwhile, Congress is trying — so far unsuccessfully — to find a way to continue funding the government.

The federal government will begin shutdown operations at midnight on Friday if lawmakers can’t pass a stopgap funding bill before then. That would grind certain services, programming and pay for federal workers to a halt, eventually affecting everyday Americans in all sorts of ways.

Could a government shutdown be the Grinch that spoils holiday travel?

While many federal employees involved in areas like air travel and border control are considered essential and are expected to keep working, a prolonged shutdown could complicate things.

Here’s what to know about planes, trains, automobiles and more.

Air travel could eventually face disruptions

The Transportation Security Administration (TSA) was already bracing for a busy holiday travel season. It expects to screen more than 39 million passengers at airports nationwide between Dec. 19 and Jan. 2.

A shutdown could throw a wrinkle in travelers’ plans, since the TSA is part of the federal government: the Department of Homeland Security.

TSA Administrator David Pekoske said Thursday that about 59,000 of the agency’s more than 62,000 employees are considered essential and would continue working without pay in the event of the shutdown.

That’s true — at least in theory.

During a five-week partial government shutdown over the 2018-2019 holiday season, scores of TSA employees — as many as 10% of the nationwide workforce — called in sick, prompting long security lines and shuttered checkpoints at some airports.

Pekoske hinted that similar problems could arise if a shutdown persists.

“While our personnel are prepared to handle high volumes of travelers and ensure safe travel, please be aware that an extended shutdown could mean longer wait times at airports,” he tweeted.

The Federal Aviation Administration (FAA), which is part of the Department of Transportation, says that more than 12,000 air traffic controllers would continue working without pay in the event of a government shutdown.

Hiring and training would be paused, however, according to its operational guidance. The FAA is already experiencing a shortage of air traffic controllers, which experts say strains the system and can exacerbate delays.

Passengers can monitor flight information online and through their airline.

In addition to the standard tips for packing and security, the TSA says travelers can prepare for potential holiday chaos by placing gifts in bags instead of wrapping them and making a plan for traveling with food — especially if they’re hoping to travel with only carry-on luggage, as many experts recommend.

Roads will be busy 

AAA predicts that 119.3 million people across the country will travel more than 50 miles from home between Saturday and Jan. 1, narrowly breaking a record previously set in 2019.

It projects that 90% of those travelers — amounting to more than 107 million people — will be making their trip by car. And because both Christmas and New Year’s Day fall on a Wednesday, it warns that traffic is likely to be especially bad on the weekends.

“There’s no set one day that’s going to be the busiest at the airports or the worst on the roads, but it’s going to be those two weekends for sure,” AAA’s Aixa Diaz told NPR’s Morning Edition this week.

That said, AAA has a list of the best and worst times to drive during the holiday period (unsurprisingly, Tuesdays and Wednesdays are the winners). And regardless of timing, it urges drivers to follow posted speed limits, slow down and move over for emergency responders, and drive only when alert.

“Driving on 4-5 hours of sleep is as dangerous as driving with a 0.08 BAC (legal intoxication),” it warns. “Less than 4 hours of sleep? The risk doubles.”

AAA advises avoiding overnight drives, heavy meals, medications that cause drowsiness and alcohol. It encourages drivers to take breaks every two hours or 100 miles, using those pauses to take a 20-30 minute nap or switch drivers if possible.

Train service is expected to continue 

While Amtrak is a for-profit company, it does receive some funding from federal and state governments. That’s not likely to be disrupted in the event of a government shutdown.

“Passengers planning to travel on Amtrak trains in the Northeast Corridor and across the country in the coming days and weeks can be assured that Amtrak will remain open for business,” Amtrak spokesperson W. Kyle Anderson told NPR over email Friday.

However, Amtrak can’t operate indefinitely without receiving disbursements of funding, the Rail Passengers Association said in a statement this week. It warns that a prolonged shutdown “will degrade service, while also slowing down upgrades being funded by the Bipartisan Infrastructure Law.”

Passport processing and border security will be largely unaffected 

The inspection and law enforcement personnel at Customs and Border Protection are considered essential, meaning that ports of entry will be open and processing of passengers will continue as usual, according to the American Immigration Lawyers Association (AILA).

While Americans still waiting on passport renewals are cutting it close for Christmas, a shutdown is not likely to further prolong that process.

The State Department’s visa and passport operations are funded by fees and therefore “not normally impacted by a lapse in appropriations,” the AILA explains.

The department’s 2023 contingency plans say that consular operations — both domestically and abroad — will remain “100% operational as long as there are sufficient fees to support operations.”

However, it says access to passport services could be suspended in certain government buildings run by agencies that have been put on pause. Luckily, Americans can now renew their passports online.