What actually closes in a US government shutdown?

Hundreds of thousands of US government defense workers, park rangers and business regulators could be temporarily out of work if Congress fails to pass a budget before a midnight Friday deadline.This time, about 850,000 workers, out of a total 3.5 million, could be told to stay home -- without pay -- until Congress reaches an agreement, the American Federation of Government Employees estimates.The 1.5 million uniformed members of the US military, mostly in the Defense Department but also 40,000