The U.S. Postal Service will deliver packages on Sundays in major cities and high volume areas during the holiday season.
Seven-day delivery will run from Nov. 17 through Christmas Day in response to anticipated growing demands.
The agency expects 12 percent growth in its package business this holiday season, or in the range of about 450 to 470 million packages.
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The Postal Service says demand for package services has grown as online retailers ship more products to their customers.
"Football has its season. But the holidays? That's our season. That's crunch time for us," Postmaster General Patrick Donahoe said, in a statement. "E-commerce package business continues to be a big player now more than ever, so we've enhanced our network to ensure America that we'll deliver their cards, gifts and letters in time for the holidays."
The struggling agency lost $2 billion this spring despite increasing its volume and charging consumers more to send mail.
The Postal Service is an independent agency that receives no tax dollars for day-to-day operations but is subject to congressional control.
For expected delivery by Christmas, the agency recommends these mailing and shipping deadlines:
— Dec. 2 - International first-class or priority mail
— Dec. 10 - International express priority mail
— Dec. 15 - Standard post
— Dec. 17 - Guaranteed global express
— Dec. 20 - Domestic first-class or priority mail
— Dec. 23 - Domestic express priority mail