With the holiday season rapidly approaching, the U.S. Postal Service wants everyone to know when to send out holiday gifts so their loved ones can receive them on time.

The following applies to the 48 contiguous states:

The deadline for Retail Ground Service is Dec. 15.

Those who opt for First-Class Mail Service, the last day is the Dec. 17.

The deadline for Priority Mail Service is a day later on Dec. 18.

Gifts sent by Priority Mail Express on the Dec. 23 might make it on time.

Here are the deadlines for sending mail to Hawaii and Alaska over the holiday season.