https://www.nbcnews.com/news/latino/...crisis-n804856

Saddled with a ballooning debt crisis, Puerto Rico has already seen a historic migration of about half a million people from the island in the past 10 years. Now, following the most powerful hurricane to hit the U.S. territory in decades, the outflow is sure to hasten.

For many Puerto Ricans, there is no alternative but to leave for the mainland: Gas is scarce, there's no running water, and only about 5 percent of the island has had power restored.

Rossello has pleaded for more aid, and warns of a mass exodus if his island doesn't get help from the federal government, which is also still contending with the aftermath of Hurricanes Harvey and Irma in the Southeast.

"There needs to be unprecedented relief for Puerto Rico so that we can start the immediate effort right now with the deployment of resources, but also the mid- to long-run recovery," he said. "If we have that, we can avoid a humanitarian crisis in the United States. But if we don’t have that, you will see thousands, if not millions, of Puerto Ricans flocking to the United States."

Tatyana Deryugina, a professor of finance at the University of Illinois who studies the economic impact of disasters, tracked Hurricane Katrina evacuees for years after the Category 5 storm ravaged New Orleans.

"I think we're going to see more advantaged people leaving, the people who have an easier time buying airfare or a boat ticket — which could be, unfortunately, some of the wealthier individuals, like doctors," she said.

The experts say there are ways to negate that. Congress could allocate money specifically for rebuilding efforts in Puerto Rico, which would attract construction companies and developers, said Deryugina, the finance professor.

Lawmakers could also allow a suspension of Puerto Rico's Promesa debt payments, Levy suggested, referring to the federal law that restructured the island's debt.

"It’s not people leaving that will be the issue, but it’s really, do you have the resources you need to fix what was damaged by the hurricane?" she said. "A year-long or longer suspension of the Promesa debt payments would mean there is money to invest in the infrastructure, schools, to make sure the hospitals are maintained."