In a surprising move that could give Amazon another huge advantage over rivals, the company on Monday announced that it will begin delivering packages to customers in two major metropolitan areas on Sundays. Working with the United States Postal Service, Amazon customers in the New York and Los Angeles regions will begin receiving deliveries on Sundays. “If you’re an Amazon Prime member, you can order a backpack for your child on Friday and be packing it for them Sunday night,” said Amazon’s operations VP Dave Clark. “We’re excited that now every day is an Amazon delivery day and we know our Prime members, who voraciously shop on Amazon, will love the additional convenience they will experience as part of this new service.” The new policy applies to Prime members and those without Amazon’s accelerated delivery service alike. Only eligible items will be delivered on Sundays, though Amazon says there are millions of items in its inventory that are eligible for Sunday deliveries. Amazon’s full press release follows below.

Amazon and the United States Postal Service Now Delivering Packages on Sunday, Making Every Day an Amazon Prime Delivery Day

Amazon customers can now get their packages on Sunday, starting in Los Angeles and New York

SEATTLE–(BUSINESS WIRE)–Nov. 11, 2013– Amazon.com, Inc. (NASDAQ: AMZN) is working with the U.S. Postal Service to deliver packages on Sunday, starting in the Los Angeles and New York metropolitan areas. Amazon Prime members, who receive unlimited, free two-day shipping on millions of items, can now receive their packages on Sunday in these areas. Amazon and the U.S. Postal Service plan to roll out this service to a large portion of the U.S. population in 2014 including Dallas, Houston, New Orleans and Phoenix, to name a few.

“If you’re an Amazon Prime member, you can order a backpack for your child on Friday and be packing it for them Sunday night,” said Dave Clark, Amazon’s vice president of worldwide operations and customer service. “We’re excited that now every day is an Amazon delivery day and we know our Prime members, who voraciously shop on Amazon, will love the additional convenience they will experience as part of this new service.”

“As online shopping continues to increase, the Postal Service is very happy to offer shippers like Amazon the option of having packages delivered on Sunday,” said Patrick R. Donahoe, Postmaster General and Chief Executive Officer. “With this new service, the Postal Service is now delivering packages seven days a week in select cities. Customers can expect the same reliable and valued service that the Postal Service currently provides.”

To participate, Amazon customers can simply add millions of eligible items to their cart and will see the Sunday delivery promise at checkout when available in their region.