AP Explains: What happens in a partial government shutdown?

A look at the impact of the partial government shutdown:
WHAT’S OPEN AND WHAT’S CLOSED
Social Security checks will go out and troops will remain at their posts. Doctors and hospitals will receive their Medicare and Medicaid reimbursements. The U.S. Postal Service, busy delivering packages for the holiday season, is an independent agency and won’t be affected. Passport services, which are funded by fees and not government spending, will also continue.
Virtually every essential g