Walmart Inc. WMT 0.17% is working with Ford F 2.80% Motor Co. and Argo AI to start testing an autonomous-vehicle delivery service in three U.S. cities as the big-box retailer’s consumers continue to favor deliveries within the same or next day.

The companies on Wednesday said the service will start in Miami, Austin, Texas, and Washington, D.C. The last-mile delivery service, or the leg of an item’s journey to the ultimate destination, will take Walmart orders to customers using Ford self-driving test vehicles equipped with Argo AI’s self-driving system.

The commercial service will be available to Walmart customers within certain areas of the three cities and will expand over time, the companies said. The initial integration testing is set to begin later this year, they added. Argo AI, a self-driving technology company, is backed by Ford and Volkswagen AG .“This collaboration will further our mission to get products to the homes of our customers with unparalleled speed and ease, and in turn, will continue to pave the way for autonomous delivery,” said Tom Ward, senior vice president of last-mile delivery at Walmart U.S.

Walmart has been delivering products from its stores for several years, using a combination of services such as DoorDash and its own service to recruit drivers to shop in its stores and deliver products. The retailer in 2018 said it was exploring delivery with self-driving cars through a partnership with Ford.

Last-mile delivery is typically dominated by large networks such as FedEx Corp. , United Parcel Service Inc. and the U.S. Postal Service. Their capabilities in same-day delivery are limited, however, as their models are built around accepting packages into their network and then sending them out.