When Hurricane Irma barreled toward Puerto Rico in September, residents worried that the island’s fragile electric grid, run by a power authority saddled with more than $9 billion in debt and a reputation for high rates and poor service, would not be able to take a direct hit.

The storm turned and grazed the northern coast of the island, knocking out power to about 1 million residents. Though shaken, Puerto Ricans breathed a slight sigh of relief. Within five days, the Puerto Rico Electric Power Authority was able to restore power to more than 70 percent of affected residents.

Then came Hurricane Maria.

Puerto Rico sustained a direct hit from that storm, which took down the entire electric grid with it and killed 34 people, though the official death toll will probably end up higher.

Flying to the island to take in the damage himself, President Donald Trump concluded yesterday that Puerto Rico should be “very proud” that more people didn’t die as compared to “a real catastrophe like Katrina.” More than 1,800 people died after that hurricane in 2005.

But living without electricity for four to six months – as PREPA had said may be the case for some parts of Puerto Rico even after Hurricane Irma – is still its own very real catastrophe.

Right now, less than 7 percent of the island has power, according to Puerto Rican government. In a sign of just how long it will take to bring back power to the rest of the grid, Puerto Rico Gov. Ricardo Rosselló said on Monday that it could take up to a month to restore power to just a quarter of households.

In the meantime, the rest will suffer in the dark.

The big question: Why will take so long to turn the lights back on in the U.S. territory?

The problem, in large part, is because of geography. When bad weather takes out power in a portion of the U.S. mainland, highly skilled workers from around the country descend upon the blackout to reconnect downed electric lines.

But in the contiguous United States, they get there by car. Puerto Rico is an island – one, as Trump memorably said, in a “very big ocean.”

Flying in the thousands of skilled workers – such as pole diggers, tree trimmers and tower installers – to begin repair work is a time-consuming logistical hassle, especially when search-and-rescue and health-care professionals need seats on planes to the island, too.

“The biggest issue is the one that everyone knows is the obvious issue, and that’s the fact that it’s island. It’s just not easy to get there,” said Mike Hyland, senior vice president of engineering services at American Public Power Association. “There are a lot of other issues too, but that’s the one that is very frustrating.”

And getting heavy equipment – such as bucket trucks, transformers and wires – to the island can take even longer because often those materials will arrive by ship from ports in Florida.

Trips by sea between Florida and Puerto Rico take several days (again, it’s in a “very big ocean”). The fact that Rosselló projected it will take several months to return power to all of Puerto Rico is a testament to the scope of the damage on the island itself.

For one thing, damage to multiple pieces of infrastructure compound the difficulty of restoring any single one of them. Take what Hyland considers to be the second-biggest challenge to bring the grid online: communication between repair crews once they’re there.

In Puerto Rico, repair crews will be caught in a Catch-22. To assess damage and deploy crews, they need to communicate with each other across the island. But to communicate, they need cell or landline service that depends on power from the electric grid.

Only when repairmen are there and talking to each other does the real work begin. The damage itself could have been worse: Although PREPA’s power stations are old – their median age is more than 40 years – they sustained only “minor damage,” according to Gil Quiniones, president of the New York Power Authority.

“The power plants are pretty much intact,” said Quiniones, who visited the island. New York state sent more than 300 employees to Puerto Rico, including two drone pilots to assess damage to the grid from the air, to provide expertise to PREPA and the Army Corps of Engineers, which on Friday was designated the lead agency for rebuilding infrastructure there.

The issue, instead, is repairing downed wires among PREPA’s 2,478 miles of transmission lines and 31,485 miles of distribution lines. Those transmission lines emanate from power plants clustered along the island’s southern coast through the mountainous, forested inland to the more populous northern part of Puerto Rico, including the capital, San Juan.

Puerto Rico’s high-voltage transmission lines, which form backbone of the grid, “do go through very mountainous, highly vegetated areas,” Hyland said.

That craggy geography, coupled with a road system that needs mending, is expected to impede the progress of electric repair crews, though according to Quiniones, “It’s nothing we haven’t done on the mainland.”

It’s the magnitude of the damage to Puerto Rico that will make the difference. As a stopgap, critical buildings, like hospitals and water-treatment facilities, will be powered by generators, which creates the additional logistical challenge of supplying them enough fuel to run.

“There is really a lot more damage than what you see on TV,” Quiniones said.

During his visit to the island, though, Trump was unwilling or unable to come to terms with the persistent power problem.

“Flashlights!” Trump said at a photo-up, holding one up to the crowd.

Then in an instant, Trump thought twice of the gesture and furrowed his brow. “You don’t need them anymore,” he said. “You don’t need them anymore.”

Salvador Sortre Vazquez , center, and his brother Angel Luis walk on the mountain in direction in what is left of their house destroyed by Hurricane Maria, in Morovis, Puerto Rico, Sunday, Oct. 1, 2017. Ramon is a cancer patient and they do not have water or electricity. (AP Photo / Ramon Espinosa)

Ramon Espinosa

Salvador Sortre Vazquez , center, and his brother Angel Luis walk on the mountain in direction in what is left of their house destroyed by Hurricane Maria, in Morovis, Puerto Rico, Sunday, Oct. 1, 2017. Ramon is a cancer patient and they do not have water or electricity. (AP Photo / Ramon Espinosa)

Ramon Espinosa