Washington braced for a government shutdown over the weekend as Congress remained mired in dysfunction on Friday. Federal agencies planned to send home hundreds of thousand workers, who would not be paid until the shutdown ended. Hundreds of thousands of others deemed essential, like air traffic controllers, would be ordered to work. They, too, would not be paid until Congress reached a deal.

The nation’s capital always feels the effects of shutdowns most acutely, but Americans beyond Washington also face consequences. Here is where they would notice them most immediately.

Food and medical help

The Special Supplemental Nutrition Program for Women, Infants and Children would run out of funding within days, jeopardizing food and medical assistance for nearly seven million mothers and children. About 10,000 children would also immediately lose access to Head Start programs.

Some of the most essential benefits, including Social Security, Medicare and Medicaid and a variety of benefits for veterans, would be unaffected. The Supplemental Nutrition Assistance Program, or SNAP, is also expected to continue through October, according to the Agriculture Department.

Business and tax support

Private businesses that depend on the federal government even in tangential ways would have to adjust.

The Small Business Administration would be forced to halt processing new loan applications. Many farmers would be similarly unable to secure loans from the Department of Agriculture around harvest season.

Routine inspections of a variety of workplaces could be limited or paused. The Occupational Safety and Health Administration would have to minimize work site safety inspections. And in the most recent shutdown, the Food and Drug Administration had to curtail food inspections at processing plants that produce fruits, vegetables and seafood.

Businesses and individual taxpayers would also run into problems.

The I.R.S. will see two-thirds of its work force furloughed, which means delayed refunds, closed call centers and no access to the National Taxpayer Advocate, an internal watchdog that helps troubleshoot problems. The revenue service normally receives 46,000 telephone calls per day in October.

National parks and forests

Many national parks and recreational areas would close their gates, hurting the surrounding communities that depend heavily on income from tourism.

Some states including Arizona and Utah have said they plan to draw on state funds to keep flagship national parks open, but a majority will close as many park rangers and forestry workers are furloughed.

Museums

The Smithsonian’s network of 21 museums and the National Zoo will use funds rolled over from the previous year and remain open until at least Oct. 7, when it has said it will re-evaluate its financial picture.

Federal courts

Federal courts have enough funds on hand to stay open for around two weeks, allowing most federal criminal cases to continue.

The Justice Department has said it will scale down its prosecution of civil cases to a bare minimum until funding is restored. Around 85 percent of Justice Department employees will continue to work, including the special counsel’s office, which will continue its prosecution of former President Donald J. Trump.

Environmental standards and disaster relief

With much of the Environmental Protection Agency’s staff set to be furloughed, the majority of the agency’s inspections at hazardous waste sites, drinking water and chemical facilities would be halted.

FEMA has also said it would be unable to continue its operations in all of the 82 major disaster sites it is currently servicing, including rebuilding from wildfires in Hawaii and hurricane recovery projects in Florida. If the shutdown persists for weeks or more, the White House has warned that FEMA’s Disaster Relief Fund could be depleted, setting up an emergency if more disasters were to occur this year.

The permitting and environmental review process for many recently launched infrastructure projects could also be disrupted because of furloughs at the E.P.A. and the Department of the Interior.

Student aid and loans

Even as much of the government is shuttered, federal student loan payments will still come due starting in October. Interest on the majority of federal student loans began to accrue again this month.

Customer service at loan-servicing companies would not halt immediately but could be tapered down should the shutdown stretch past next week.

On Monday, Karine Jean-Pierre, the White House press secretary, said that processing for Federal Student Aid and Pell Grants should continue mostly unaffected for “a couple of weeks.”

Travel

Air traffic controllers and Transportation Security Administration officials will continue to work without pay and attempt to minimize flight disruptions. But trainings for new air traffic control staff workers would be paused as many airports are already experiencing shortages.

During the last shutdown, conditions for workers were so bad that T.S.A. employees considered walking off the job, which helped to hasten an agreement in Congress to end the shutdown.

Passport processing, which already takes around 10 to 13 weeks, will continue but could be limited by government building closures in some locations that house passport processing offices.

Amtrak is expected to continue regular service.