TAMPA — Online retail giant Amazon has opened two enormous distribution centers in the greater Tampa Bay area in the past two years. The company made same-day delivery available to much of the region and, in some cases, within one hour. From here, Amazon also coordinates deliveries to large swaths of the Southeast.That means millions of packages are gushing out of those warehouses — one in Ruskin, the other in Lakeland — every week.So where does all the merchandise to stock those facilities come from?Amazon goods are flowing into Tampa International Airport daily aboard a Boeing 767 cargo freighter plane. Then it's all shuttled away to the nearby warehouses on Amazon trucks, where the merchandise is sorted, packed and shipped to customers' doors. All that Amazon activity has increased the Tampa airport's cargo activity by 20 percent so far this year compared with last year. The deal has generated more than $275,500 in revenue for the airport over the past seven months in fees and building rental payments, a number which should double by the end of the year, according to airport records. The daily flight, which comes to Tampa from Wilmington, Ohio, is part of a national deal that Amazon quietly inked with Air Transport Services Group in September to lease five Boeing 767 cargo planes and use them to move merchandise across the country. Tampa was among one of the first regions to be a part of Amazon's air cargo delivery network. Every day, an ABX Air plane is unloaded and merchandise is stored in rented warehouse space on airport property. Amazon trucks can be seen leaving the airport stock full of goods on their way to the Ruskin and Lakeland centers, which are 1 million square feet each.Amazon and ATSG renewed the contract in April and extended the lease to 20 cargo planes. This is the latest move by the online retail giant to have complete control over its user experience. By controlling the shipping process, Amazon is able to speed up its deliveries and can avoid problems often associated with using third-party vendors, like in 2013 when FedEx and UPS struggled to deliver holiday orders on time. There are reports that Amazon wants to acquire its own cargo planes from Boeing, which would give the retailer even more control over how and when its orders are shipped. Tampa airport has become a key cog in that process as Amazon continues to stretch its services, including its same-day delivery, which is now available in only a handful of U.S. metro areas, including Tampa Bay. In April, Amazon launched its Prime Now service in the Tampa Bay area, where Prime customers could get deliveries shipped for free to their door within two hours. Some items can be delivered in an hour for a fee. Amazon signed a lease for a warehouse space in the Adamo Distribution Center in Tampa before launching the Prime Now service."Amazon has had a tremendous impact on Florida. Not only have they invested hundreds of millions of dollars in capital investment to build new facilities across the state, but they have also helped to diversify our economy by creating more jobs than initially expected," said Sean Helton, spokesman for Enterprise Florida.Amazon representatives did not return calls and emails requesting comment. Officials with the Tampa airport declined to comment."Essentially, we supply all aspects of the air operation, including flying and maintaining the planes, loading and unloading freight, arranging and managing the airport facilities," Paul Cunningham, spokesman for ABX Air, said in an email. He declined to elaborate further because "we prefer not to disclose without the customer's consent, which they have not given."One of the cargo companies under the ATSG umbrella, Air General Inc., leased a 12,546-square-foot warehouse at Tampa International Airport in November, where the Amazon-leased cargo planes unload and store merchandise, according to Hillsborough County Aviation Authority reports. Contact Justine Griffin at [email protected] Follow @SunBizGriffin.