Drone-delivery businesses cropped up all over the globe in recent years, but most focused on last-mile logistics for food and retail. The concept of air dropping a burrito to a hungry college co-ed is a fun one. But one drone-delivery business that has pulled ahead of the pack, Zipline, gained commercial traction by flying lifesaving medical supplies to thousands of rural clinics instead.

Now Zipline, which ranked No. 39 on the 2019 CNBC Disruptor 50 list, has raised $190 million in venture funding and attained a $1.2 billion valuation from its investors. Its backers include Baillie Gifford, The Rise Fund (which is TPG's global impact fund), Temasek, Alphabet's investment arm GV and Katalyst Ventures. The funding brings Zipline's total capital raised to $225 million.

CEO Keller Rinaudo, who co-founded Zipline with Keenan Wyrobek and William Hetzler in 2011, says that with the new funding, Zipline will be able to set up delivery hubs at 2,600 health facilities in Rwanda and Ghana by the end of this year. And it will soon be making deliveries of medical supplies in the U.S., starting in North Carolina, where it has secured permission from the FAA to do so.

"People think what we do is solving a developing economies problem. But critical-access hospitals are closing at an alarming rate in the U.S., too, especially if you live in the rural U.S. Life expectancy there has declined over the past several years," Rinaudo said.

According to data from the National Center for Health Statistics, drug overdose deaths have been a major factor in lower life expectancy in the U.S, especially in rural areas.