More than three months have passed since Hurricane Maria's 155-mph winds plowed through Puerto Rico leaving the island severely crippled and desperate for help.

The storm — which knocked out all power and most cell phone service — was the worst disaster to ever hit the Caribbean island, home to 3.4 million American citizens.

The reaction from the White House was one of the ugliest moments of President Trump's administration this year. When Trump visited Puerto Rico two weeks after the storm, he suggested that Maria wasn’t “a real catastrophe” like Hurricane Katrina. And instead of offering condolences, he reminded Puerto Rico about how much money it was costing the federal government to respond to the crisis.

He then walked around throwing paper towel supplies to hurricane survivors, and spent weeks insulting the mayor of San Juan on Twitter after she accused the federal government of abandoning Puerto Rico.

Helping Puerto Rico recover is a gargantuan task — FEMA has called it the "largest federal response to a disaster" in American history. But this response has also been unusually painful to watch, with the shady contracting deals, a drinking water crisis, and the army of federal responders stretched too thin to effectively get help to everyone quickly. Congress was slow to respond too. Many lawmakers visited the island, but Congressional leaders have done little to help the island beyond voting to add more money to FEMA’s disaster-relief fund.

The island is limping back to some semblance of normalcy as the New Year approaches. But hundreds of thousands have fled as the conditions fail to improve. More than a third of the island still has no power, and federal workers are still sending food and water supplies to some towns.

Here are five important things to know about Puerto Rico 100 days after Maria:

1) Electricity probably won’t be entirely restored before May

The single biggest problem facing Puerto Rico is still the lack of power. Gov. Ricardo Rosselló promised that 95 percent of the island would have power by now. Only 65 percent does.

On Thursday, protests broke out across the island, in towns such as Trujillo Alto and Aquas Buenas, which have not had any power since the hurricane.

The blackout is now the largest in US history. Just take a look at this chart published by the research firm Rhodium Group:

There are many reasons why it’s been so hard to restore power. For one, the power grid was a mess before the storm hit. The public utility company, PREPA, had been putting off repairs for years as the island sank into a deep economic recession. The utility company is also bankrupt and understaffed, as thousands of electrical workers have retired or moved to the US mainland in the past decade to find better jobs.

While the storm didn’t destroy the entire power grid, it did knock down 80 percent of the island's utility poles and all transmission lines. And because Puerto Rico's government is broke, it didn’t have the money to start repairing the grid right away. Instead, the head of PREPA at the time, Ricardo Ramos, signed two questionable contracts with little-known private American energy companies that required little payment up front. Ramos planned to pay the rest of the contracts with reconstruction grants from FEMA.

The main energy contract never got the far. It was a massive $300 million deal with Whitefish Energy, a tiny Montana company that had two employees at the time.

A Congressional investigation later found that Whitefish Energy ended up charging Puerto Rico more than double the regular wages for utility crew line workers and higher-than-normal daily meal rates, and included clauses making it hard for PREPA to enforce a timeline.

The public backlash led Ramos to cancel the contract and resign from his job, and PREPA had to find a new contractor.

Now the US Army Corps of Engineers is overseeing grid repair contracts with more experienced utility crews from the mainland. But the logistics are still a mess. Building and shipping thousands of utility poles and power lines to the island, then setting them up on mountainous terrain has become a headache for utility crews. Roberto Ferdman, a reporter for Vice News, described the logistical nightmare:

On top of that, right now, Puerto Rico is competing with Texas, California, Florida, and the U.S. Virgin Islands, all of which need these sorts of materials too. The result: more than 50k utility poles have been ordered, but only about 11k have been delivered to the island so far — Roberto Ferdman (@robferdman) December 20, 2017

The new estimate, he says, is that utility workers will restore power to 95 percent of PREPA’s customers by the end of February, and to 100 percent of them by the end of May.

“Puerto Ricans don’t necessarily believe that,” Ferdman tweeted. “And why should they? The original estimate was December 15th...About a third of the island is still in the dark.”

2) Hundreds of thousands of Puerto Ricans have fled the island, probably for good

The blackout, food shortages, and unreliable running water plaguing Puerto Rico in Maria’s aftermath have triggered an exodus from the island.

It's impossible to know exactly how many Puerto Ricans have left, but more than 269,000 people have arrived in Florida on flights from Puerto Rico since the hurricane, according to the Florida Division of Emergency Management.

Some people are staying with relatives, some have decided to relocate to the US mainland; others are staying at hotels paid for by FEMA. Most Puerto Ricans have headed to Florida.

Before the hurricane, the Orlando area had seen a surge of migration from Puerto Ricans leaving the island for job opportunities in the United States as a result of the recession.

That pattern of migration has sped up since the hurricane.

Demographers expect the Maria to trigger an even larger migration in the long term. The Center for Puerto Rican Studies at the City University of New York estimates that Puerto Rico will lose up 470,335 residents by the end of 2019 — about 14 percent of the population.

They believe that many of them will move in Florida — up to 82,000 people a year.

The migration has already impacted Florida. More than 10,000 Puerto Rican children have enrolled in Florida’s public schools in the past three months.

On January 15, FEMA’s voucher program to cover hotel costs for displaced families will expire for Puerto Rican disaster victims. This has led Florida lawmakers to panic over the possibility of finding shelter for thousands of Americans who have nowhere else to go.

“There are tens of thousands of families living in Florida,” state Sen. Victor Torres (D-Orlando) said in a statement Wednesday to the Orlando Weekly. “If just one family becomes homeless due to lack of action by the federal government or those officials making decisions in Puerto Rico, it is one family too many.”

3) FEMA is overwhelmed

FEMA responders are stretched thin, to say the least. Aside from Puerto Rico, the agency is responding to multiple federal disaster zones in California, Texas, and Florida.

It’s the longest activation in FEMA’s history, and the agency is “tapped out,” FEMA administrator Brock Long told lawmakers at a November 30 Congressional hearing.

“It is time to question what is FEMA’s role in disaster management and emergency recovery,” Long told members of the House Appropriations Committee. “Let’s hit the reset button. FEMA was never designed to be first or only respondent in a disaster, but we often find ourselves in that situation.”

The reconstruction of Puerto Rico is arguably the agency's most challenging mission ever. As FEMA has moved from emergency response to recovery mode, it's now focused on providing federal grants to rebuild public buildings, help homeowners repair homes, and provide loans to small businesses.

But reconstruction is difficult when residents are still in a state of emergency —without power or proper shelter. FEMA said it is still distributing tarps, food, and water to some communities. More than 450 people are still living in shelters.

The agency has also been inundated with 1 million applications for individual disaster assistance, which is aid for disaster victims who lost their homes and jobs and need money for temporary shelter or to pay their bills, among other challenges. So far, FEMA has approved 350,000 individual aid requests, adding up to about $705 million, said FEMA spokesman Daniel Llargues.

The agency is also reviewing grant applications from local governments who need help rebuilding schools, roads and other infrastructure. All 78 municipalities in Puerto Rico have applied for these reconstruction grants, Llargues said, and all of them have had grants approved. So far, FEMA has wired $453 million to Puerto Rican government agencies to rebuild. That includes $60 million for the Department of Transportation to start fixing 15 impassible bridges, according to El Nuevo Día newspaper.

Here’s a chart FEMA made to remind people of the gargantuan efforts the agency has made in Puerto Rico since the hurricane hit:

4) The government still doesn't know how many people died

More than 90 days after the hurricane hit, the government has no idea how many people died as a result of the storm. The governor recently ordered a recount.

The official hurricane death toll has been a source of controversy since President Trump visited the island on October 3 and congratulated Gov. Ricardo Rosselló for the low number of deaths. At that time, the number was six. The official death count —now at 64 — has since been disputed by the press (including Vox), by academics, and by members of Congress.

In November, Vox published an analysis by social science researchers who used mortality data from the Puerto Rico Vital Statistics System to compare the historical death averages for September and October and found that the number of people who died from the storm is closer to 1,085. A New York Times analysis of similar data found that the death toll could be at least 1,052.

This prompted two members of Congress, Rep. Nydia Velázquez (D-NY) and Rep. Bennie Thompson (D-MS), to request a federal investigation by the Government Accountability Office. In a letter to the head of the GAO, they said they worried that the death toll had been “artificially suppressed.”

Five days later, Rosselló ordered a recount of all hurricane deaths.

Staff from Puerto Rico's Public Safety Department and Demographic Registry will investigate each death recorded in the hurricane's aftermath, regardless of the official cause of death listed on the death certificate, Rosselló said. He did not give details about how the investigation will work or how long it will take.

But many are skeptical about Rosselló’s ability to provide accurate estimates at this point. Rep. Velázquez said she will continue to press for an independent federal review.

5) Trump failed Puerto Rico

President Trump is ultimately responsible for what happens in Puerto Rico.

Under the Stafford Act, the president takes the lead role in disaster response and recovery in all 50 states and Puerto Rico. He could unilaterally order FEMA and other federal agencies to send more people or direct more resources to the island.

Trump could also publicly pressure the governor to be more forthcoming about the death count. The local government surely shares the blame for the slow response, but the president is ultimately responsible for the lives of the 3.4 million US citizens on the island.

His casual treatment of their struggle may come back to haunt Republicans. Puerto Ricans who live on the island may not have a voting member in Congress, but once they move to the United States, they do.

With hundreds of thousands of Puerto Ricans fleeing the island, they will likely voice their frustrations in the voting booth in the coming midterm elections.