Congress has until tomorrow to pass a spending bill, or the government will run out of money and shut down. That means most federal services, other than those deemed "essential" — such as those working for the Department of Homeland Security or Department of Defense — will close temporarily.

Why it matters: Even if you aren't a government employee, a shutdown can still affect you personally, from how your tax dollars are spent to which tourists sites you can't visit.

Here's what to expect:

• Mail: The U.S. Postal Service is an independent agency that doesn't rely on tax dollars to operate, so your mail will still be delivered.
• Your wallet: The last time the government shut down — for 16 days in 2013 — it cost taxpayers $2 billion in lost productivity, according to the Office of Management and Budget.
• Vacation: All national parks, museums, and zoos will be closed. You might also have trouble getting a passport. There could also be some airline and train delays, as "non-essential" employees will be furloughed.
• Food stamps: You can still collect these. The Supplemental Nutrition Assistance Program (SNAP) is a mandatory entitlement program.
• Federal courts: The courts won't close their doors immediately, but they could be affected if a shutdown lasts more than 10 days, according to past guidance.
• Social security: You will still receive payments under the program, as it is deemed mandatory by the government.
• Loans: Whether you own a small business or are planning to buy a house, if you need a loan from the government, you'll have to wait.