The American companies Ford and Walmart will soon begin working together to design a delivery service that uses self-driving vehicles. The project grew out of the car company Ford’s efforts to develop businesses that could use self-driving delivery vehicles. Ford has already been working with the delivery company Postmates to develop the service. Ford said its new project with Walmart will take place in and around Miami, Florida. The project will deliver goods ordered at Walmart stores through Postmates. It will begin with human-driven vehicles to see how a self-driving vehicle would behave. Ford has said it expects to launch wider production of self-driving vehicles by 2021. Brian Wolf is with Ford’s self-driving vehicle group. He wrote in a blog post that the companies will test to see which goods, especially groceries, can be delivered successfully. In a statement, Tom Ward of Walmart said, “Before self-driving cars can go mainstream, we must get a better sense of how people want to interact with them.”