There will be no mail delivery and you won't be able to ship a package or mail a letter on Monday.
Many post office locations have 24-hour access to paid post office boxes, but you won't get any new mail in your box on Monday.
You can purchase stamps at automated kiosks at many post offices nationwide, but your letter or package won't go out until Tuesday.
Not only are all U.S. post offices closed on October 14, all federal offices, including the DMV and Social Security, are closed on Monday.
The current government shutdown has forced the closure of many federal offices, so Monday may be just another unpaid day off for many furloughed workers if there is no resolution over the weekend.
If you need to mail a package, you will have to wait until October 15 to send it out. In addition, delivery will resume to homes and businesses on Tuesday.
Click here for a full list of U.S. postal holidays.