Walmart customers in six states will soon be able to have their orders delivered by drone in less than 30 minutes.

Why it matters: This will be the first large-scale drone delivery operation in the United States. So far, drone deliveries have been available only in a few small towns, with customers selecting from a short list of items.

Driving the news: Walmart's DroneUp delivery network will expand to 34 sites by the end of the year, potentially reaching 4 million U.S. households, the retailer said.

The scale of Walmart's planned operation is significant in other ways too.

The big picture: The race to bring drone delivery to U.S. households is shaping up as a battle of titans, as everyone from Amazon and Alphabet to UPS and Domino's invests.

The intrigue: Walmart and DroneUp will offset the cost of delivery with revenue from other drone-related services, such as insurance inspections, emergency response and construction oversight.

Of note: Walmart is a minority investor in DroneUp and has a seat on its five-member board.

What they're saying: The Federal Aviation Administration is paying close attention to what Walmart and DroneUp are doing as it prepares regulations that will allow widespread drone deployment over longer distances.

The big picture: Drone delivery is the latest effort by Walmart to expand customers' delivery options.