The White House has begun advising federal agencies to prepare for a government shutdown as Republican lawmakers have shown no signs of progress in negotiations to keep the government funded beyond this week.

The United States has experienced 21 gaps in government funding since 1976, leading to varying degrees of disruption. Under a worst-case scenario, the White House is warily eyeing a repeat of 2018, the longest and most recent shutdown, which sidelined roughly 800,000 of the federal government’s 2.1 million employees for 34 days.

While much remains uncertain about how inevitable a shutdown may be or how long one may last, the broad contours of how it would play out are well-worn territory in Washington, and most agencies have readied plans for working through the tumult.

A government shutdown amounts to a suspension of many government operations until Congress acts to restore funding.

For hundreds of thousands of federal employees, that means either being furloughed while the government is closed, or continuing to work without pay.

For the public, that typically means dealing with interruptions to a variety of government services and facing a range of inconveniences and disruptions to daily life.

In recent days, the White House has spotlighted several government programs that could cause more severe issues if suspended, in particular the nutrition and immunization assistance given out through the Special Supplemental Nutrition Program for Women, Infants and Children. If funding lapses, the White House has said nearly seven million women and children could lose critical access to food, and the federal contingency fund to keep the program running could run dry within days.

“If we have a shutdown, WIC shuts down, and that means the nutrition assistance to those moms and young children shuts down,” Tom Vilsack, the agriculture secretary, told reporters on Monday.

Closures of national parks and museums are often one of the most visible impacts of a shutdown for the public, as well. In some cases, they can produce significant losses for the communities that depend on tourism.

Gov. Katie Hobbs of Arizona, for instance, has vowed to draw on revenue from the Arizona Lottery to keep Grand Canyon National Park open. In 2021, the park drew more than 4.5 million visitors to the state, according to the National Park Service.

Even many workers in the private sector are often forced to adjust.

During the most recent shutdown, inspections of chemical factories, power plants and water treatment plants ground to a halt as the Environmental Protection Agency furloughed thousands of workers. The Food and Drug Administration also paused routine food safety inspections of seafood, fruits and vegetables, putting extra pressure on restaurants and grocers.

In addition, many government labs and research projects are frequently closed during prolonged shutdowns, hampering scientific work.

As the deadline to fund the government approaches, the White House has sought to stress the sheer variety of programs and services that would suffer while blaming House Republicans for the standoff.

“A government shutdown could impact everything from food safety to cancer research to Head Start programs for children,” President Biden said on Saturday.

Many agencies whose employees carry out critical services do not suspend operations.

That includes a large number of federal prosecutors and investigators, postal workers and Transportation Security Administration employees.

Most of those employees will continue to work without pay until funding is restored. In rare cases, some may work in positions that are funded outside the annual appropriations process.

Benefits such as Medicare and Social Security also continue uninterrupted because they are authorized by Congress in separate laws that do not need to be renewed every year. Medical care of veterans also goes on unaffected.

But even in instances where federal workers may stay on the job, planning and operations supporting them can be suspended, making the work harder.

For instance, while air traffic controllers would largely continue to work, trainings for new staff members would cease, exacerbating shortages.

Having weathered multiple shutdowns already, most agencies have in place detailed contingency plans for determining which employees should keep working.

But those plans can vary widely.

According to its contingency plan, the Department of Health and Human Services plans to retain about 58 percent of its employees during a shutdown, while the Justice Department would direct closer to 85 percent of its employees to continue working.

The determinations for each agency are often based on workers’ roles and how precisely their jobs are deemed “necessary to protect life and property.”

Shutdowns have become so commonplace in Washington that the Office of Management and Budget publishes guidance for federal employees on what to expect when one is approaching.

Yes.

In Article I, Section 6 of the Constitution, compensation for members of Congress is differentiated from that of most federal workers.

“The senators and representatives shall receive a compensation for their services, to be ascertained by law, and paid out of the Treasury of the United States,” that section reads.

In addition, the language of the 27th Amendment, which prohibits any law “varying the compensation for the services of the senators and representatives” until the next election, is often interpreted as a constitutional requirement that lawmakers be paid on time.

Salaries for members of Congress are funded by a permanent appropriations account that does not require renewal every year.

Like federal agencies, lawmakers also have some limited discretion to keep staff members working in cases where their role is directly tied to human health and safety. This typically applies only to staff members whose work is “required to support Congress with its constitutional responsibilities or those necessary to protect life and property,” according to the Congressional Research Service.

Furloughed employees will get back pay once Congress passes and the president signs a new appropriations bill or a continuing resolution.

Employees who worked overtime or earned other premium pay can typically also claim those extra wages once the shutdown ends.