Amazon Partners with USPS for Fresh Grocery Delivery has partnered with the United States Postal Service in a two-month trial where USPS delivers insulated containers of meat, produce, dairy and other groceries to Amazon’s customers in San Francisco. The deliveries are made between 3 a.m. and 7 a.m. when the Postal Service trucks are not in high demand and since the products are shipped in insulated containers, refrigerated trucks are not needed. The AmazonFresh unit also delivers groceries in Seattle and Los Angeles using its own trucks, but if the USPS trial is a success, it could open new markets to the e-commerce service. Amazon also is testing its own same-day delivery system in certain markets and could offer its AmazonFresh service in 20 urban areas by the end of the year.

A successful partnership could also help the USPS, which is aggressively targeting package deliveries to help stem the $2 billion in losses it experienced between April and June; it now delivers 3.7 billion packages per year, a 20 percent increase in five years. "We work with Amazon. They're an excellent, excellent customer and an excellent partner. We'd like to deliver their groceries," said Postmaster General Patrick R. Donahoe in an interview with the Wall Street Journal. "As the Postal Service, we visit every house, every day. Why not?"

The Postal Service currently is Amazon’s largest shipper, carrying about 35 percent of the 608 million packages the company shipped in 2013.