But Puerto Rico has to wait until American boats can reach its shores with supplies because of an obscure, World War I-era shipping law that the Trump administration is refusing to waive.
Trump's decision to keep the Jones Act in place is also feeding into a narrative that the president is aloof to Puerto Rico's problems. His administration lifted the Jones Act to help Texas and Florida after hurricanes Harvey in August and Irma this month.
Meanwhile, despite agitation from powerful members in Congress to get rid of the law entirely so we don't keep having these debates after hurricanes, it's likely to stay on the books.
Here's what you need to know about the Jones Act.
What the Jones Act does: It requires that ships going from American coast to American coast be American - built, owned, flagged and crewed. That means goods going from the mainland to Puerto Rico, Hawaii, Alaska and Guam, or even from Texas to New England, have to travel on U.S. ships, even if they're not the most economical transport or readily available.
Why that matters to hurricane relief: The law means than foreign ships in nearby countries can't just zoom over to Puerto Rico with aid supplies. They either have to pay tariffs for landing at a U.S. port, or they would have to go to Florida first to drop off their goods with a Puerto Rico-bound U.S. ship.
"A foreign relief shipment to Puerto Rico, they have two choices," said Scott Miller, an international trade expert with the Center for Strategic & International Studies. "One is to land in San Juan and pay tariffs associated with the Jones Act, or to take shipments to Jacksonville, offload the ship and reload it on a U.S. one."
Puerto Rican officials have long despised the law, arguing that it makes their food and goods much more expensive than on the mainland. Politicians in Hawaii have argued that ranchers have even resorted to flying cows to the mainland rather than shipping them. Other opponents of the law say it forces New Englanders to pay more for propane, holds up salt supplies to clear snowstorms in New Jersey and raises electricity rates in Florida.
But now, Puerto Rican officials say, it's a matter of life and death. The entire island is in a communications and power blackout, Washingon Post reporters there say: "Estimates for the return of electricity and basic services will be measured not in days but in weeks and months."
But the Department of Homeland Security said that getting more fuel to the island wouldn't address its main problem, which is ports damaged by the storm. Plus, barges would deliver humanitarian relief, which make up a large part of U.S.-flagged ships, the agency said.
Why the law exists: Congress passed the Merchant Marine Act in 1920, after World War I, when Congress was worried that the U.S. shipping industry was weak - too weak to, say, fight with German submarines that had sunk hundreds of U.S. ships.
Why the law still exists: Sen. John McCain, R-Ariz., has been leading the charge to get rid of it. It's antiquated, it hinders free trade and it makes goods more expensive, he argues.
But the U.S. shipping industry likes the law because it guarantees them jobs. And that may be enough of a reason. "The power of this maritime lobby is as powerful as anybody or any organization I have run up against in my political career," McCain said in 2014.
Trump himself said as much when chatting with reporters briefly Wednesday: "We're thinking" about lifting it, he said, but "a lot of people who are in the shipping industry don't want it" lifted.
Why it probably will exist for the foreseeable future: The Jones Act has long had powerful friends. For a while, shipyards in Mississippi were the main beneficiaries of the Jones Act, and a senator from Mississippi, Trent Lott, R, happened to be the Senate majority leader.
Conversely, many who lose out under the Jones Act don't have a say. Puerto Rico, for example, has no voting power in Congress. Same with Guam.
"It's a classic residual program that has concentrated benefits to a few and widely diffused costs to the many," Miller said.
Why the Trump administration is taking heat: It bolsters criticism that Trump cares a lot less about Puerto Rico than he does about U.S. citizens on the mainland.
Over the weekend, Trump tweeted more than a dozen times about NFL players kneeling during the national anthem and not once about the devastation in Puerto Rico. Trump even appeared to be unclear on how far away Puerto Rico is from the mainland United States, saying there's "a very big ocean" rescuers have to cross to get there.
And it gives his opponents another data point to use when they accuse Trump of being more empathetic to the plights of people who look like him.