Visitors to Mesa Verde National Park are advised to use “extreme caution” during a partial federal government shutdown that began midnight Friday.

Large signs at the entrance to the visitors center and main entrance to the park state the National Park Service is unable to fully staff the park, but it is also not feasible to close or prohibit access to all parks.

As employees are not able to provide guidance, assistance, maintenance or emergency response, entrance to the park is “at the visitor’s sole risk,” the sign states. The NPS will not issue permits, collect trash, provide restrooms, provide visitor information or plow roads.

“In the event of a government shutdown, national parks will remain as accessible as possible while still following all applicable laws and procedures,” National Park Service Chief Spokesperson Jeremy Barnum said in an email to The Journal on Friday. “For example, this means that roads that have already been open will remain open and vault toilets will remain open.”

In Montezuma County, 40 percent of land is owned by the federal government. Mesa Verde National Park encompasses 52,000 acres, or 82 square miles, of federal land managed by the NPS. Canyons of the Ancients National Monument encompasses 176,000 acres, or 275 square miles, of federal land under the Bureau of Land Management.

Visitor centers at Rocky Mountain National Park were locked Saturday and roads were closed or unplowed.

But the U.S. military said the shutdown won’t affect NORAD Tracks Santa, its 63-year-tradition of answering phone calls from children on Christmas Eve asking where Santa Claus is at the moment. The operation is run from Peterson Air Force Base in Colorado Springs.

Rocky Mountain National Park’s gates were open, but staffing was cut back and roads were not being cleared of new snow.

Roads that were passable at the time of the shutdown would remain open unless conditions worsened, park spokeswoman Kyle Patterson said.

“This is really disappointing,” said Sarah Schlesinger of Boulder, who went to the park with two nieces from Florida who had never seen snow before.

“It’s time for a new administration,” she said.

Rocky Mountain National Park is the fourth most popular national park in the country, drawing 4.4 million visitors in 2017. It lies 65 miles from downtown Denver.

Other national parks in Colorado – Great Sand Dunes and Black Canyon of the Gunnison – said on their Facebook pages that some areas remained accessible but that could change without notice and no ranger services were available. Dinosaur National Monument in northwestern Colorado had the same message on its Facebook page.

Bent’s Old Fort National Historic Site was closed to protect park resources and visitors, said Rick Wallner, the site’s chief of interpretation.

Hikers who already have backcountry permits can still hike down into the Grand Canyon in northern Arizona. But visitors arriving at Carlsbad Caverns National Park in southern New Mexico can check out only the surface, not the underground cavern that is the park’s main attraction. While roads, hiking trails and boating ramps are open and available for use at numerous parks and monuments in the region, visitor centers and other staffed facilities at many are closed because of the shutdown.

Still others, particularly those with precious natural and cultural treasures, are closed entirely and off limits because of the shutdown resulting from a Washington, D.C., deadlock over President Donald Trump’s desire for funding for a U.S.-Mexico border wall.

Sites closed outright include Bandelier National Monument in northern New Mexico, home to irreplaceable petroglyphs and cliff dwellings, and Petrified National Forest National Park in northern Arizona, where even on a normal day people are tempted to illegally remove pieces of petrified wood as souvenirs.

Closures padlocked gates at Casa Grande Ruins National Monument in south-central Arizona, White Sands National Monument in southern New Mexico and Valles Caldera National Preserve, home of scenic mountain meadows where a volcano erupted about 1.2 million years ago in what is now northern New Mexico. Valles Caldera was closed “for the safety and protection of visitors and park resources,” its announcement said.

It may not be easy in some cases to determine from afar the status of some Interior Department parks and monuments. Like some others, Bandelier’s website on Saturday was topped by a shutdown notice that said the website itself “will not be updated and may not reflect current conditions.”

But state officials made clear that some of the region’s big draws for tourists remained open, at least in terms of access and basic services.

Arizona and Utah officials implemented funding plans to keep open Grand Canyon, Zion, Arches, Bryce Canyon and Zion national parks and provide services such as public restrooms, shuttles and trash collection. Concession operations such as lodges remained open, and Utah’s funding for the parks in that state included visitor centers.

Utah Gov. Gary Herbert said his state wanted visitors who planned their visits months in advance “to return home with memories of magnificent vistas and welcoming people, not locked doors.”

Similarly, Arizona Gov. Doug Ducey said visitors should stick to plans to visit the Grand Canyon. “The Grand Canyon will not close on our watch,” he said in a statement announcing the state funding.

However, Carlsbad Caverns said its roads, lookouts and trails were available to visitors. But the park’s status report added, “the visitor center and cavern will be closed.”

Near Las Vegas in southern Nevada, Lake Mead National Recreation Area remained open, but officials cautioned that emergency and rescue services will be limited there and at Tule Springs Fossil Beds National Monument. Similar warnings were posted in other parks and monuments where many employees were furloughed.

President Donald Trump, who previously said he would “take the mantle” of a shutdown, on Friday said the shutdown could drag on “for a very long time.” The Associated Press reports that more than 800,000 federal workers face furloughs or will be forced to work without pay during the shutdown.

Nine of 15 Cabinet-level departments and dozens of agencies would face a lapse in funding, including the departments of Homeland Security, Transportation, Interior, Agriculture, State and Justice, as well as national parks and forests.

Many agencies, including the Pentagon and the departments of Veterans Affairs and Health and Human Services, are funded for the year and would continue to operate as usual. The U.S. Postal Service, busy delivering packages for the holiday season, would not be affected by any government shutdown because it’s an independent agency.

The Associated Press contributed to this report.