During the closing months of his four-year run as US Secretary of Transportation, Foxx has come to California on a fact finding mission alongside Keller Rinaudo, CEO of Zipline. The startup just launched the world’s first national drone delivery service, carrying blood and other medical supplies around Rwanda. Foxx wants to know what they’re all about—and how the same sort of business might work in the United States.

The former mayor of Charlotte, North Carolina has taken what may seem a drab job—enforcing car safety regulations, putting up highway signs, and the like—and used it to push emerging technologies closer to consumers. In September, his DOT released guidelines defining a new approach to regulating self-driving cars. He launched the Smart City Challenge, a $50 million competition that pushed urban centers to prepare for the future. And under Foxx’s direction, the FAA finally opened the skies to commercial drone operations, albeit with a couple of serious restrictions: no deliveries, and no flying past the human operator’s line of sight.

After seeing the drone fly, Foxx takes a tour of Zipline’s lab, peppering Rinaudo with technical queries: How does the drone deal with weather, how high can it fly, what’s its useful life? Then he asks his bigger question: “How have we been to work with?” Rinaudo compliments the new regulations—the FAA’s first serious step to encourage the technology—but he’s itching for the feds to drop the leash. He insists beyond line of sight flights are totally safe, and that the current ban on drone deliveries hampers worthy projects, like delivering vital medicine to rural communities.

As the CEO makes his pitch, Foxx nods. He’s all for the technology and is impressed by what Zipline has pulled off so far. But he knows the field, knows the FAA values safety above any commercial goal, and that, with some 30,000 domestic flights everyday, American airspace is the world’s most complicated. He sympathizes, but promises nothing. “I can’t push the FAA that fast,” he says.

“I totally get the level of urgency from folks in industry who see all kinds of applications,” Foxx says. He sees the potential, too: to beam internet all over the world, to transform medical supply chains, to get people their Amazon packages even faster. “But we’re not dealing with a complete green field here. There are other users of our airspace. The challenge for us is an integration challenge.”

That challenge will take a while to solve, says Arthur Holland Michel, co-director of the Center for the Study of the Drone at Bard College. He compares “drone years” to “dog years”—they move at a different pace than the breakneck innovation Silicon Valley heralds. The good news for companies like Zipline, Michel says, is that the FAA’s current regulations allow for lots of exceptions, whether it’s to fly at night, or over people (both currently no-no’s). “It does not feel like the FAA is dragging its feet,” he says. “There’s an eye to the rules evolving.”

So, how long until Zipline can start catapulting its drones through US airspace? Michel won’t venture a guess, but says it’s inevitable that the rules will evolve, even if the safety-obsessed FAA takes its time.

Foxx is glad he helped push the traditionally stodgy government this far, but knows he won’t be around to finish the job. “It’s bittersweet,” he says. “I’ll leave things a little less complete than I would like to.”

Come January, it will be up to the Trump Administration to give the FAA that next big push.