Expect some of the best attractions the District has to offer ​to get shuttered in a government shutdown.

The city’s free museums and monuments lock their doors; National Park Service sites turn away visitors.

“Sites will generally be closed and areas that remain accessible to the public will face significantly reduced services,” according to the Park Service’s shutdown contingency plan.

While park facilities that are typically locked or secured during non-business hours will be closed during a shutdown, other places, such as outdoor areas, can still be used by the public.

“Generally, where parks have accessible park areas, including park roads, lookouts, trails, campgrounds, and open-air memorials, these areas will remain physically accessible to the public,” the plan said.

The District’s official tourism website warns that many federally funded attractions will be closed, such as the U.S. Capitol Visitors Center, Botanic Garden and Library of Congress.

The Smithsonian Institution, which receives over 60% of its funding from the federal government, may face closure after Oct. 6 if the government isn’t funded by then, affecting 21 museums and the National Zoo, according to the institution.

“In the event of a federal government shutdown, the Smithsonian will use prior-year funds to remain open to the public at least through Monday, Oct. 6, 2025,” the institution said Tuesday.

It said any updates will be added to the Smithsonian website.

The institution made a similar move during the 2018 shutdown — the museums and zoo remained open for 11 days by using reserve funds.

If national parks were kept open, it would be in stark contrast to the 2013 shutdown under President Obama, when park entrances were closed and barriers were placed around national monuments and memorials.

Most famously, veterans broke past the barricade at the World War II memorial to lay wreaths and protest its closure. Republicans, at the time, accused Mr. Obama of closing the sites out of spite.

In official Washington and in federal offices across the country, about 750,000 workers are furloughed each day the government is shut down, according to the Congressional Budget Office.

The daily cost of their salaries equals roughly $400 million, Phillip Swagel, the director of the CBO, said in a recent letter to lawmakers.

“The effects of a shutdown depend on its duration and on an Administration’s decisions about how to proceed,” Mr. Swagel wrote. “The number of furloughed employees could vary by the day because some agencies might furlough more employees the longer a shutdown persists and others might recall some initially furloughed employees.”

And yet, the essential functions of government will persist.

The military and most federal law enforcement personnel remain on the job, though they will not get paid until the shutdown ends. That includes workers at the Department of Homeland Security, such as at Customs and Border Protection, Immigration and Customs Enforcement, the Transportation and Security Administration, Citizenship and Immigration Services, the Secret Service and the Federal Emergency Management Agency.

Only about 14,000 of Homeland Security’s 271,000 employees will be furloughed.

Medicare and Medicaid payments will still be distributed, but will likely be delayed due to staffing shortages.

The Food and Drug Administration will continue responding to public health issues and handling product recalls and drug shortages, with 86% of employees staying on the job.

Services such as Amtrak and the U.S. Postal Service will continue running, because they are independent agencies funded through the sales of products and services and not through taxpayer money appropriated by Congress.

• This article is based in part on wire service reports.

• Mallory Wilson can be reached at mwilson@washingtontimes.com.