Starting in September 2015, people in the city noticed more planes flying in and out of the airport, loading and unloading those black-wrapped boxes. This March, Amazon announced that it was leasing 20 Boeing 767s from Air Transport Services Group, a cargo company that operates out of the air park. Amazon had also negotiated an option to buy nearly 20 percent of the company. ... Two months after the Ohio announcement, Amazon leased 20 more jets from Atlas Air, an air cargo company based in Purchase, N.Y. Amazon has also purchased 4,000 truck trailers. Meanwhile, a company subsidiary in China has obtained a freight-forwarding license that analysts say enables it to sell space on container ships traveling between Asia and the U.S. and Europe. In short, Amazon is becoming a kind of e-commerce Walmart with a FedEx attached. ... Amazon’s ambitions depend on the continued success of its Prime service. For $99 a year, Amazon Prime customers get two-day delivery at no extra charge. Those who sign up tend to spend almost three times as much as their non-Prime peers. The company zealously guards its numbers, but Consumer Intelligence Research Partners estimates that Amazon had 63 million Prime members as of late June—19 million more than the year before.