Edward C. Baig

USA TODAY

NEW YORK — Don't let the weekend get in the way of your next online package delivery.

Amazon.com's Sunday delivery program is now available in 15 additional cities, beyond the New York and Los Angeles metro areas where the program originally launched last November, the online retailer announced Thursday.

Amazon Prime members who order an eligible item as late as Friday can receive the package — delivered by the U.S. Postal Service — as soon as Sunday, under the free two-day shipping benefit that comes with the $99 annual Prime membership.

The additional markets: Austin; Cincinnati; College Station, Texas; Columbus; Dallas; Houston; Indianapolis; Lexington, Ky.; Louisville; New Orleans; Oklahoma City; Philadelphia; San Antonio; Shreveport, La.; and Waco, Texas. Amazon plans to roll out the program to more of the U.S. population during the year.

Amazon says "millions" of products qualify for Sunday delivery. "So far, the most common items delivered on Sunday include baby supplies such as newborn apparel, books and toys — Sunday delivery is clearly crossing errands off the weekend to-do list," said Mike Roth, Amazon's vice president of North America operations.

Does Amazon's Sunday expansion signal a similar move by rivals? "In terms of who's likely to be next, I'd be looking to some extent at the other largest online retailers, and that includes Staples, Wal-Mart, Office Depot, OfficeMax, Sears, QVC, Best Buy and Macy's," says Jan Dawson, chief analyst at Jackdaw Research. "But it's probably best positioned by most of those retailers as a premium service for people who need certain items urgently, and they'd pay accordingly."

Still, Dawson expects Amazon to be it for the time being. "I just don't see the urgency for other retailers, especially those that have chains of retail stores open on Sundays. In some ways, this is more about Amazon plugging a hole in its model — making items available on Sundays — than it is about stealing a march on others."

But Brendan Connaughton, chief investment officer at ClearPath Capital Partners in San Francisco, believes Amazon's Sunday push puts added pressure on rival retailers. "I think it's going to just make it tougher for their competitors to compete against them. The thing about Amazon is it is a category killer and an industry killer."

Amazon Prime customers don't have to do anything special to take advantage of Sunday shipping. If a purchased item is available for Sunday delivery in a given region, Amazon consumers will see that option when they add the item to their shopping carts during checkout. Non-Prime customers can get Sunday delivery as well, but they must pay standard shipping rates.

Amazon delivers some of its own packages through AmazonFresh, its online grocery business. It sends packages through FedEx, UPS and other distributors. The expansion of the Sunday delivery program provides a much-needed boost to the struggling U.S. Postal Service, which has been seeking ways to tap into the growth of online shopping and is for now Amazon's exclusive Sunday distribution partner.

"We're pleased to be delivering more packages on Sunday and just allowing the shippers and customers to appreciate the benefits of U.S. Mail," says Sue Brennan, a U.S. Postal Service spokeswoman. "This is a win-win for both organizations, and we do hope it expands."

Brennan says that the Postal Service has been talking with other companies about Sunday delivery but would not disclose details.

She says Amazon packages slated for Sunday delivery must reach postal distribution centers by Sunday morning. The Postal Service has hired flexible part-time employees to help with Sunday delivery and same-day delivery.

Amazon's stock closed at 288.32 Thursday, down 1.5%.