The federal government is nearing a partial shutdown, with a range of effects on public services and the broader U.S. economy.

Employee furloughs and potential layoffs would halt some government activities. Other functions — like NASA’s space missions, President DonaldTrump’s immigration crackdown and certain public health work at FDA and the USDA — would continue.

Here is a look at some of what’s expected across agencies:

Most Department of Homeland Security employees would continue to work, because much of the department’s workforce is connected to law enforcement or works in areas funded by user fees as opposed to Congressional appropriations.

DHS said in a plan published on its website that about 14,000 of the agency’s roughly 271,000 employees would be furloughed in the event of a government shutdown. That would include maintaining the vast majority of officers and employees at Customs and Border Protection, Immigration and Customs Enforcement, the Transportation and Security Administration, Citizenship and Immigration Services and the Federal Emergency Management Agency, among other divisions.

Department activities such as providing Secret Service protection for Trump, processing cargo and passengers coming into the country and carrying out the Trump administration’s immigration enforcement operations would continue, the plan said.

Medicare and Medicaid programs and services will also continue uninterrupted, though staffing shortages could mean delays for some services, like the mailing of Medicare cards.

The government has enough money to fund Medicaid for the first quarter of the next fiscal year, according to the Department of Health and Human Services. Also, eligible states will continue receiving payments from the Children’s Health Insurance Program, or CHIP.

No plan yet for national parks

The National Park Service has not said whether it will close its more than 400 sites across the U.S. to visitors.

Park officials said Tuesday afternoon that contingency plans were still being updated and would be posted to the service’s website.

Many national parks, including Yellowstone and Yosemite, stayed open during a 35-day shutdown during Trump’s first term. Limited staffing led to vandalism, gates being pried open and other problems including an off-roader mowing down one of the namesake trees at Joshua Tree National Park in California.

A group of former national park superintendents last week called for parks to close in case of a shutdown to protect park resources and visitor safety. States including Utah, Colorado and New York donated money to keep some national park sites open during past shutdowns.

FEMA fallout could block some new mortgages

While FEMA’s core disaster relief functions would not be affected, at least in the short term, other aspects of the agency’s work would be impacted. Some grant approvals would be paused, and no new policies could be written under the National Flood Insurance Program, halting new mortgages that require flood insurance.

Still, an extended shutdown could, in a worst-case scenario, exhaust FEMA’s existing Disaster Relief Fund, which stands at about $10 billion. House Speaker Mike Johnson warned Monday at the White House that FEMA “won’t be funded” during a shutdown.

Air traffic controllers will keep working

Air traffic controllers already certified and on the job would be among the essential workers who would continue during any shutdown but their pay could be affected.

National Air Traffic Controllers Association President Nick Daniels has said that having to work without a paycheck adds stress to controllers who already do a difficult job. He said that in past shutdowns some controllers have even had to get side jobs to help pay bills while the shutdown drug on.

Capt. Jason Ambrosi, president of the Air Line Pilots Association, urged Congress to reach an agreement. “A shutdown threatens the stability of the safest aviation system in the world,” Ambrosi said.