Visitors to Washington, D.C., who thought the Smithsonian museums were immune to the government shutdown are in for a big disappointment next week.

If the shutdown continues beyond New Year’s Day, the museum network will be forced to close all its doors along the National Mall and at the National Zoo. The closures would begin on Jan. 2 and continue until lawmakers reach a deal to fund the government.

Because the museums have so far remained open, many people assumed the Smithsonian Institution was among the roughly three-quarters of government functions that Congress had already appropriated money for before the partial shutdown began on Dec. 22.

But Smithsonian spokeswoman Linda St. Thomas explained that it had been running on last year’s funds to get through the week between Christmas and New Year’s ― typically one of the busiest times of the year. The Smithsonian Institution receives its federal dollars through an appropriations bill that also funds the Interior Department, which is among the unfunded agencies.

“We used prior-year funding, and we can’t continue to do that,” St. Thomas said. “I think it was a great service to tourists, but on Jan. 2 and beyond we will be closed” until a deal is reached.

A closure of the Smithsonian would be just one way that everyday Americans will feel the effects of the shutdown, even if they don’t work for the federal government. The shuttered properties would include the American History Museum, the Air and Space Museum, the African American Museum and the Portrait Gallery, as well as more than a dozen others.

President Donald Trump has said the shutdown will continue until lawmakers agree to provide $5 billion for a wall along the southern border that he originally said Mexico would pay for. House Republicans have said they have no plans to hold a vote before the new year, leaving the shutdown with no end in sight. An agreement that meets Trump’s full demands is even less likely after Jan. 3, when Democrats take over as the House majority.

The shutdown has left 420,000 federal employees working without pay, and another 380,000 furloughed without a job. It will require an act of Congress to retroactively pay those workers once the government reopens. There is no guarantee that will happen, although it typically has in the past.

St. Thomas said roughly two-thirds of the Smithsonian’s employees are federal workers; the rest are paid through the Smithsonian trust. If the museums and zoo are forced to close, only certain workers like security and building maintenance personnel will remain on the job.

Many workers would be unlucky enough to lose their wages even if Congress approves backpay after the shutdown ends. That’s because they work for an outside contractor rather than the federal government. According to St. Thomas, the museum shops are run by the Smithsonian, but cafeteria workers are employed by an outside company called Restaurant Associates.

If the 2013 government shutdown is any indication, those workers may end up having to apply for unemployment insurance if the shutdown persists, as any day not working is a day without pay. A company spokesman declined to comment when asked how many Restaurant Associates employees would be affected by a shutdown.

Even though the zoo would be closed, St. Thomas said veterinarians and other workers who feed and care for the animals there would still be on duty throughout a shutdown.

“The minute there’s funding, we open,” she said.

CORRECTION: A previous version of this story mistakenly indicated the Smithsonian is receives its funding through the Department of Interior.