Walmart is expanding drone delivery across six states this year, making it possible for many more customers to get a box of diapers or dinner ingredients delivered in 30 minutes or less.

Through an expansion with operator DroneUp, the big-box retailer said it will be able to reach 4 million households in parts of Arizona, Arkansas, Florida, Texas, Utah and Virginia. The deliveries by air will be fulfilled from a total of 37 stores — with 34 of those run by DroneUp.

It announced its plans for growth on Tuesday in a blog post. Walmart currently offers drone deliveries from a few stores near its headquarters in northwest Arkansas and in North Carolina.

Walmart has been testing how the small, unmanned aircraft could change the game for retail, drive e-commerce growth and turn its stores into a way to outmatch Amazon on speed. Two years ago, it struck deals with three operators — Flytrex, Zipline and DroneUp — and began pilot projects to deliver groceries, household essentials and at-home Covid-19 test kits to customers. The company declined to share terms of the deals.

The new kind of delivery is an extension of Walmart’s strategy to use its huge physical footprint as a competitive edge. About 90% of Americans live within 10 miles of one of Walmart’s more than 4,700 stores. Through those stores, Walmart has offered a growing list of fast online options including curbside pickup; InHome, which delivers directly to customers’ fridges; and Express Delivery, which drops items at doorsteps in two hours or less.