WASHINGTON >> If the government "shuts down" next Tuesday, your mail will still come. Doctors will see Medicare patients. NASA will keep talking to the astronauts circling Earth on the Space Station. In fact, the majority of government will remain on the job.

The bad news would hit random Americans first: vacationers hoping to take in Mount Rushmore or a Smithsonian museum. Homebuyers seeking government-backed mortgages. Travelers who want new passports, quickly. Perhaps on the bright side — for some — tax audits would probably be suspended.

Troubles would spread the longer a shutdown lasted.

A prolonged furlough of more than one-third of civilian federal workers could mean delays in processing applications for new Social Security and Medicare benefits. Lost profits for businesses that sell goods or services to the government. Problems for airlines and some hotels and restaurants that rely on tourism near national parks. Longer waits for kids seeking delinquent child support.

And, of course, a shutdown would mean no paychecks for an estimated 800,000 furloughed workers. They might get paid later for the missed days but couldn’t count on that.

The deadline nearing, a government of more than 2.1 million civilian employees scrambled on Friday to update its plans determining who would stay and who would go home, what would get done and what would have to wait. The equation was complicated by the complexity of federal budget rules; some pots of money would be caught up in a shutdown and some wouldn’t.

Ironically, a shutdown would have virtually no impact on President Barack Obama’s health care law — the program at the heart of his showdown with House Republicans. The program that detractors dubbed "Obamacare" is set to roll out its individual insurance plans on Tuesday, government shutdown or no, and people hoping to sign up on that first day shouldn’t be affected.

Other work expected to continue no matter how the political fight goes:

— Prison guards, federal law officers and Border Patrol agents will be at their posts.

— Air traffic controllers and airport security screeners will keep airports open.

–The military’s 1.4 million active-duty personnel will stay on duty.

–Social Security payments will still go out. Doctors will see Medicare and Medicaid patients. Food stamp dollars should continue to flow.

–NASA will man Mission Control in Houston to support the International Space Station and the two Americans among six people living aboard. But aside from that, only about 3 percent of NASA’s 18,000 workers will be on the job.

–The White House will stay open because it’s exempted from the federal law that requires many government employees to stop working if congressionally approved funding for their jobs expires. Obama could still take his scheduled trip to Asia the week of Oct. 6, if he chose to.

–The post office will keep delivering; its budget isn’t affected because it comes from selling stamps and delivering packages.

— U.S. Citizenship and Immigration Services employees who work on programs funded by user fees — including processing green card applications — will also stay on the job.

–Federal courts have enough money to operate normally for about 10 days, and their workers will be paid. But if a shutdown continued past mid-October, furloughs would begin.

One reason a shutdown would balloon over time concerns the legion of private contractors who carry out many of the government’s functions. Some are paid through huge long-term contracts that wouldn’t be affected anytime soon or their money comes from protected streams. Others would see their payments cut off but would keep their employees working for as long as they could, expecting the government to pay its tab eventually. But as cash ran low they might have to turn to layoffs.

For tourists and nature lovers, the effects would start immediately. A shutdown would quickly close all national parks, from Acadia to Yosemite, and national monuments and wildlife refuges. The Interior Department says campers would get 48 hours to pack up and leave.