Government Shutdown in the U.S. - What will happen?

(This has been copied from an article)
Much of the federal government is headed toward a shutdown as of midnight EDT. What will be closing, why and what impact will it have?

Question: Why a shutdown?

Answer: Every year, Congress has to approve laws, known as appropriations, that provide money for federal agencies. The new budget year begins Oct. 1, and Congress has failed to pass a single one of the appropriations. An effort to pass a stopgap bill to provide temporary money has stalled in Congress: Republicans have insisted they will not approve the stopgap measure unless Democrats agree to block money for President Barack Obama's health care law, and Democrats have refused to do that. Under federal law, if an agency does not have an appropriation law in force, it can't spend money, so it has to close.

Q: Do all government programs stop?

A: No. There are three big categories that don't. Some programs don't require annual appropriations. That group, which includes Social Security, Medicare and other so-called entitlements, continues without interruption. The second group entails functions "necessary to protect life or property." Law enforcement, the military, intelligence agencies and foreign embassies all will stay open. Finally, some programs have other sources of money that will allow them to function for a while. Courts, for example, can spend money they have collected through fines and fees, funds that would allow them to keep functioning for a while.

Q: What are some examples of government offices that will close?

A: The national parks, federally owned museums, such as the Smithsonian, offices overseas that give visas to foreigners hoping to visit the United States, many federal regulatory agencies, IRS call centers that provide assistance to taxpayers and most offices that handle federal grants and contracts will all close.

Q: What happens to federal workers?

A: At least 800,000 federal civilian workers will be furloughed. They will not be paid during the shutdown.

Q: Will workers get back pay once the shutdown ends?

A: The last time this happened, during the Clinton administration, Congress approved retroactive pay. There's no guarantee, however.

Q: What impact will all this have on the economy?

A: A lot depends on how long a shutdown lasts. If the duration is only a few days, the economic impact will be small. But the impact builds with time. The tourism industry will be among the first hit because of the closure of parks and the inability of foreign tourists to get visas.

Q: Why hasn't Congress passed its appropriations bills on time?

A: Passing money bills has been difficult for years because of disputes between the two parties about how much to spend. This year, the problem got a lot worse after House Republicans passed a budget plan that called for deep cuts in spending. When the time came to translate those overall spending numbers into specific appropriations bills, the bills failed because many Republicans decided the spending levels were too low.

Q: How long will a shutdown last?

A: Both Republicans and Democrats will be watching to see which side gets blamed for the impasse. Whichever side is losing the battle for public opinion will eventually decide the price has gotten too high and will offer concessions. In the Clinton administration, there were two government shutdowns. One lasted five days, the other, which affected only part of the government, went on for three weeks.

TL;DR:
not much has changed