Amazon is shuttering its drone delivery operations in Lockeford, California, one of the earliest U.S. test sites for the decade-long project.

The program, called Prime Air, has struggled to get off the ground since Amazon founder Jeff Bezos first detailed his vision in 2013 of autonomous drones delivering packages weighing less than 5 pounds in 30 minutes or less.

Amazon said in a blog post on Monday that it intends to keep expanding drone deliveries to more U.S. cities in 2025, and plans to open up in part of the Phoenix area later this year. The company said it’s working with the Federal Aviation Administration and local officials to get permission for drone deliveries in Tolleson, west of Phoenix.

“As we look to the future and prioritize our resources to continue growing the program, we’ve also made the decision to close our delivery site in Lockeford,” the company wrote. Amazon said it will offer employees opportunities at other sites, and Lockeford residents can still place orders using other delivery methods.

Amazon says it’s now conducting test flights to demonstrate the reliability of its new delivery drone, the MK30, which the company unveiled at an event last year. The drone is intended to be smaller and quieter than prior models, and can fly through light rain.

Amazon in 2020 received Part 135 certification from the Federal Aviation Administration, allowing it to use drones to deliver packages with some restrictions. But Prime Air’s progress has been delayed.

In 2022, Amazon said it would begin testing deliveries in College Station, Texas, about 100 miles northwest of Houston, and Lockeford, a town south of Sacramento where the program’s arrival was initially met with some skepticism by residents.

Just as it looked set to get going, Prime Air was hit by layoffs last year as part of broader job cuts at Amazon. The group also encountered regulatory setbacks and executive departures.

Amazon has still continued to push ahead with expanding drone deliveries. Last October, the company cleared a significant regulatory hurdle when the FAA loosened some restrictions on where its drones can operate, permitting it to fly over roadways and cars when necessary to complete a route.

Last week, Amazon signed a deal with Embention, a developer of autopilot systems and components for drones. As part of the agreement, Embention will provide Amazon with safety-related hardware and software.

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