A look at which services may or may not be affected in a shutdown:
Federal air traffic controllers, airport screeners and federal inspectors would stay on the job.
The State Department would process foreign applications for visas and U.S. applications for passports. Embassies and consulates overseas would provide services to U.S. citizens.
Social Security and Medicare benefits would keep coming, but there could be delays in processing new disability applications. Unemployment benefits would still go out.
Federal courts would continue operating normally for about 10 business days. After that, the judiciary would have to begin furloughs of some employees, but cases would continue to be heard.
Deliveries would continue.
All national parks would be closed, as would the Smithsonian museums, including the National Zoo in Washington. Visitors using overnight campgrounds or other park facilities would be given 48 hours to make alternate arrangements. Among the centers that would be closed: the Statue of Liberty and Ellis Island in New York, Independence Hall in Philadelphia, Alcatraz Island near San Francisco and the Washington Monument.
New patients would not be accepted into research at the National Institutes of Health, but current patients would receive care. The Centers for Disease Control and Prevention would be limited in spotting or investigating outbreaks.
Federal meat inspections would be expected to proceed.
The Administration for Children and Families says grants expiring about Oct. 1 would not be renewed.
The Special Supplemental Nutrition Program for Women, Infants and Children, known as WIC, could shut down. School lunches and breakfasts would be served, and food stamps would be distributed.
Americans would still have to pay their taxes and file federal tax returns, but the IRS would suspend audits and shut help lines.
Many low-to-moderate incomes borrowers and first-time home buyers seeking government-backed mortgages could face delays during the shutdown. Action on government-backed loans to small businesses would be suspended.
The majority of the Department of Homeland Security’s employees are expected to stay on the job, including uniformed agents and officers at the country’s borders and ports of entry, members of the Coast Guard, Transportation Security Administration officers, Secret Service and other law enforcement agents and officers. U.S. Citizenship and Immigration Services employees would continue to process green card applications.
The military’s 1.4 million active duty personnel would stay on duty, but their paychecks would be delayed. About half of the Defense Department’s civilian employees would be furloughed.
Most Veterans Affairs services will continue. Veterans could visit hospitals; operators would still staff the crisis hot line, and claims workers would still process payments. But those veterans appealing the denial of disability benefits will have to wait longer for a decision because the board would not issue any decisions during a shutdown.
Federal occupational safety and health inspectors would stop most workplace inspections.