Delivery drones are so fast they can zip a pint of ice cream to a customer's driveway before it melts.

Yet the long-promised technology has been slow to take off in the United States. More than six years after the Federal Aviation Administration approved commercial home deliveries with drones, the service mostly has been confined to a few suburbs and rural areas.

That could soon change. The FAA proposed a new rule last week that would make it easier for companies to fly drones outside of an operator's line of sight and therefore over longer distances. A handful of companies do that now, but they had to obtain waivers and certification as an air carrier to deliver packages.

While the rule is intended to streamline the process, authorized retailers and drone companies that have tested fulfilling orders from the sky say they plan to make drone-based deliveries available to millions more U.S. households.

Walmart and Wing, a drone company owned by Google parent Alphabet, currently provide deliveries from 18 Walmart stores in the Dallas area. By next summer, they expect to expand to 100 Walmart stores in Atlanta; Charlotte, North Carolina; Houston; and Orlando and Tampa, Florida.

After launching its Prime Air delivery service in College Station, Texas, in late 2022, Amazon received FAA permission last year to operate autonomous drones that fly beyond a pilot's line of sight. The e-commerce company has since expand its drone delivery program to suburban Phoenix and has plans to offer the service in Dallas, San Antonio, Texas, and Kansas City.

The concept of drone delivery has been around for well over a decade. Drone maker Zipline, which works with Walmart in Arkansas and the Dallas-Fort Worth area, began making deliveries to hospitals in Rwanda in 2016. Israel-based Flytrex, one of the drone companies DoorDash works with to carry out orders, launched drone delivery to households in Iceland in 2017.

But Wing CEO Adam Woodworth said drone delivery has been in "treading water mode" in the U.S. for years, with service providers afraid to scale up because the regulatory framework wasn't in place.

"You want to be at the right moment where there's an overlap between the customer demand, the partner demand, the technical readiness and the regulatory readiness," Woodworth said. "I think that we're reaching that planetary alignment right now."

DoorDash, which works with both Wing and Flytrex, tested drone drop-offs in rural Virginia and greater Dallas before announcing an expansion into Charlotte. Getting takeout food this way may sound futuristic, but it's starting to feel normal in suburban Brisbane, Australia, where DoorDash has employed delivery drones for several years, said Harrison Shih, who leads the company's drone program.

"It comes so fast and it's something flying into your neighborhood, but it really does seem like part of everyday life," Shih said.

Even though delivery drones are still considered novel, the cargo they carry can be pretty mundane. Walmart said the top items from the more than 150,000 drone deliveries the nation's largest retailer has completed since 2021 include ice cream, eggs and Reese's Peanut Butter Cups.

Unlike traditional delivery, where one driver may have a truck full of packages, drones generally deliver one small order at a time. Wing's drones can carry packages weighing up to 2.5 pounds. They can travel up to 12 miles round trip. One pilot can oversee up to 32 drones.

Zipline has a drone that can carry up to 4 pounds and fly 120 miles round trip. Some drones, like Amazon's, can carry heavier packages.

Once an order is placed, it's packaged for flight and attached to a drone at a launch site. The drone automatically finds a route that avoids obstacles. A pilot observes as the aircraft flies to its destinations and lowers its cargo to the ground with retractable cords.

Shakiba Enayati, an assistant professor of supply chain and analytics at the University of Missouri, St. Louis, researches ways that drones could speed the delivery of critical health supplies like donated organs and blood samples. The unmanned aircraft offer some advantages as a transport method, such as reduced emissions and improved access to goods for rural residents, Enayati said.

But she also sees plenty of obstacles. Right now, it costs around $13.50 per delivery to carry a package by drone versus $2 for a traditional vehicle, Enayati said. Drones need well-trained employees to oversee them and can have a hard time in certain weather.

Drones also can have mid-air collisions or tumble from the sky. But people have accepted the risk of road accidents because they know the advantages of driving, Enayati said. She thinks the same thing could happen with drones, especially as improved technology reduces the chance for errors.

Woodworth added that U.S. airspace is tightly controlled, and companies need to demonstrate to the FAA that their drones are safe and reliable before they are cleared to fly. Even under the proposed new rules, the FAA would set detailed requirements for drone operators.

"That's why it takes so long to build a business in the space. But I think it leads to everybody fundamentally building higher quality things," Woodworth said.

Others worry that drones may potentially replace human delivery drivers. Shih thinks that's unlikely. One of DoorDash's most popular items is 24-packs of water, Shih said, which aren't realistic for existing drones to ferry.

"I believe that drone delivery can be fairly ubiquitous and can cover a lot of things. We just don't think its probable today that it'll carry a 40-pound bag of dog food to you," Shih said.

DoorDash said that in the areas where it offers drone deliveries, orders requiring the services of human delivery drivers also increase.

That's been the experience of John Kim, the owner of PurePoke restaurant in Frisco, Texas. Kim signed on to offer drone deliveries through DoorDash last year. He doesn't know what percentage of his DoorDash customers are choosing the service instead of regular delivery, but his overall DoorDash orders are up 15% this year.

Kim said he's heard no complaints from drone delivery customers.

"It's very stable, maybe even better than some of the drivers that toss it in the back with all the other orders," Kim said.

For some, drones can simply be a nuisance. When the FAA asked for public comments on Amazon's request to expand deliveries in College Station, numerous residents expressed concern that drones with cameras violated their privacy. Amazon says its drones use cameras and sensors to navigate and avoid obstacles but may record overhead videos of people while completing a delivery.

Other residents complained about noise.

"It sounds like a giant nagging mosquito," one respondent wrote. Amazon has since released a quieter drone.

But others love the service. Janet Toth of Frisco, Texas, said she saw drone deliveries in Korea years ago and wondered why the U.S. didn't have them. So she was thrilled when DoorDash began providing drone delivery in her neighborhood.

Toth now orders drone delivery a few times a month. Her 9-year-old daughter Julep said friends often come over to watch the drone.

"I love to go outside, wave at the drone, say 'Thank you' and get the food," Julep Toth said.

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AP Video Journalist Kendria LaFleur contributed from Frisco, Texas.