Amazon said Friday it'll begin delivering packages to residents of College Station, Texas, later this year, the second location in the United States for its Prime Air delivery service and the latest in an expansion of the technology that emerged this week.

College Station, about 80 miles northwest of Houston, is home to Texas A&M University, which has a drone research program that's already several years old. The e-commerce giant in June also announced plans to begin drone deliveries in Lockeford, California, near Sacramento. 

Amazon helped kick off the drone delivery idea with the 2013 announcement of Prime Air. But abundant challenges slowed the technology's arrival: safety, regulatory approval, autonomous navigation, bad weather, cost, and finding a good way to hand off packages.

Now drone delivery is picking up, promising one-hour delivery times for thousands of items in Amazon's warehouses and other options from drone delivery rivals. This week, Zipline announced medical package delivery plans near Tacoma, Washington, and Alphabet's Wing debuted new drone designs for larger and smaller packages. With partner DroneUp, Walmart expects to deliver packages via drone in Arizona, Arkansas, Florida, Texas, Utah and Virginia for a $4 delivery fee. UPS, Flytrex, Manna and others also are delivering packages around the world.

After testing many models, Amazon settled on drones that use a hexagonal design and take off vertically. They tilt in flight so some struts of the hexagonal frame become wings that generate lift and improve range. They fly 400 feet above the ground at speeds up to 50 mph carrying packages up to 5 pounds.

Amazon's drones have a 15km range -- about 9 miles.

The US Federal Aviation Administration has certified Amazon's operations, but Amazon is working with FAA and local authorities overseeing its Lockeford and College Station projects, Amazon spokesperson Av Raichura Zammit said.

Delivery drones can raise hackles among people concerned about safety, privacy and noise.

To address those kinds of concerns, Amazon has been talking to local residents and plans events to get community feedback and show them what's planned, Zammit said.