Amazon is preparing a roughly sixfold expansion of its Prime Air drone delivery network, targeting nearly 500 U.S. cities and towns by the end of 2026 as retailers and delivery companies race to make last-mile shipping faster and cheaper.The rollout would dramatically widen Prime Air's footprint from 11 current delivery sites across 10 metro areas and give Amazon a larger test of whether autonomous aircraft can become a meaningful part of its logistics network.Amazon plans to expand next into the Chicago, Atlanta, Cleveland, Syracuse and Boise metropolitan areas, with additional communities ex...