While most of the country has had Sunday delivery from Amazon.com Inc. for a while, the service is finally rolling out to the Twin Cities and other parts of the Upper Midwest now that the online retailer's "sortation center" in Shakopee is up and running.

The sorting center is not to be confused with the 820,000-square-foot fulfillment center Amazon is building in the same southern suburb. That project, which drew headlines this spring and will employ about 1,000 people, is still under construction.

Amazon's sorting center drew less attention as the online retailer quietly set up shop in an existing 150,000-square-foot facility a few miles from the larger site. Amazon launched operations there last month with more than 300 employees.

"It's because of the sortation center network that we're able to offer Sunday delivery for our customers," said Nina Lindsey, an Amazon spokeswoman. "We are now able to offer Sunday delivery to a majority of the U.S. population."

The first Sunday deliveries in the Twin Cities began in a soft launch to a handful of areas on Aug. 16 and has been ramped up to a wider region since then. The service is also now available in Fargo, Duluth, Rochester and Sioux Falls.

Amazon first launched Sunday delivery in New York and Los Angeles in 2013 and has since expanded it to most major U.S. markets. Amazon has been working to win customers over by promising even faster delivery.

In July 2014, Amazon unveiled its first sorting centers, where orders that have been packed at fulfillment centers are sent to be sorted by ZIP code. Amazon then drops those packages off at the post office for that ZIP code. The U.S. Postal Service delivers the packages to customers' doorsteps, including the Sunday deliveries. Amazon now has more than 20 sorting centers in the U.S.

The addition of the Shakopee sorting center also means that customers in the region now have a longer window in which they can place orders for same-day processing. That cutoff time, previously 2:59 p.m., is now midnight.

In April, Shakopee city officials confirmed that Amazon planned to build the fulfillment center. The plan initially faced some opposition because of some proposed tax subsidies. But the controversy died down when Amazon agreed to forgo a few million dollars in assistance. The project has received some indirect support through a $5.8 million tax-increment financing district set up to pay for road improvements near the site.

"They are two independent locations," Shakopee Mayor Brad Tabke said Thursday of the Amazon sorting and fulfillment centers. "We are really excited that Shakopee ended up with both of them."

Amazon has not yet given a completion date for its fulfillment center. But once Amazon has more of this infrastructure in place, Twin Cities customers might soon be able to get same-day delivery. Amazon already offers it in more than a dozen metro areas.

"We haven't made any announcement yet," Lindsey said when asked when it would arrive in the Twin Cities. "But stay tuned."

And then after that, perhaps, it's on to the drones.