Roy Vaussine and Charlotte Biagas live in modest, single-story homes about a dozen miles apart in southwest Louisiana. When Hurricane Laura tore through their community last August, the damage was nearly identical. A tree crashed through the roof of each house. Neither had insurance. Each sought help from the federal government.

At that point, their stories diverge. The Federal Emergency Management Agency initially gave Mr. Vaussine $17,000 in assistance; Ms. Biagas and her husband, Norman, got $7,000.

Their situations are different in another respect: Mr. Vaussine is white. Charlotte and Norman Biagas are Black.

A growing body of research shows that FEMA, the government agency responsible for helping Americans recover from disasters, often helps white disaster victims more than people of color, even when the amount of damage is the same. Not only do individual white Americans often receive more aid from FEMA; so do the communities in which they live, according to several recent studies based on federal data.

Leaders at FEMA are wrestling with the complicated question of why these disparities exist — and what to do about them. The problem seems to stem from complex systemic factors, like a real estate market that often places higher values on properties in communities with many white residents, or the difficulty of navigating the federal bureaucracy, which tends to favor people and communities that have more resources from the beginning.

The impact from this disparity is long-lasting. White people in counties with significant disaster damage that received FEMA help saw their personal wealth jump years later while Black residents lost wealth, research published in 2018 shows.

The imbalance comes as climate change fuels more frequent and more destructive storms, wildfires and other disasters, and marginalized communities tend to be both the most exposed to damage and least able to recover financially.

FEMA declined to comment on individual cases, citing privacy concerns, and said it had created an internal working group to examine the issue. In April, it asked the public for examples of policies “that perpetuate systemic barriers to opportunities and benefits for people of color and/or other underserved groups,” as well as ideas for improvement.

“We are advancing this work,” said Justin Knighten, FEMA’s director of external affairs, adding that the agency is working on a comprehensive public response. “That is a top priority for the administrator.”

The racial disparities in FEMA’s disaster assistance present a test for President Biden, who has made fighting both racial inequality and climate change central themes of his administration.

“All FEMA programs and policies need to be equitable, due to the disproportionate impact of disasters on marginalized communities,” said Chauncia Willis, co-founder and chief executive of the Institute for Diversity and Inclusion in Emergency Management, a nonprofit group in Georgia. “It needs to become a core goal.”

The pressure on FEMA to address racial disparities is growing. The Government Accountability Office is looking at FEMA’s actions “to ensure more equitable outcomes” in its disaster programs. The agency’s own advisory council said FEMA isn’t meeting its legal requirement to provide aid without discrimination on racial or other grounds. During her Senate confirmation, the first question faced by Deanne Criswell, President Biden’s choice to run FEMA, was how she would ensure Black, brown and Latino survivors get equal access to disaster aid.

“It is unacceptable that minority communities not only feel the impact of natural disasters far more severely than others, but they also often have more difficulty obtaining assistance from the federal government,” Senator Gary Peters, Democrat of Michigan and chairman of the Homeland Security and Governmental Affairs Committee, said in a statement

The research so far suggests that the scale of the problem is immense.

After a disaster, FEMA’s Individual Assistance program offers grants to survivors who do not have insurance, providing as much as $36,000 for home repairs. Before giving money, FEMA or its contractors inspect a property for damage, and then determine whether that damage was caused by the disaster and how much to provide in assistance.

Ethan J. Raker, who recently earned a Ph.D. at Harvard and will be taking up an assistant professor position at the University of British Columbia this summer, used a public record request to obtain 5.4 million applications for FEMA assistance from homeowners affected by hurricanes between 2005 and 2016. He found racial disparities at every stage of the process.

The higher the percentage of Black residents living in a specific ZIP code, the less likely applicants there were to get an inspection, without which FEMA typically will not fund repairs, he found.

Even when disaster victims in African-American neighborhoods were able to get a damage inspection, 11 percent had their requests denied with no reason given. By comparison, just 4 percent of homeowners in white neighborhoods were denied with no reason given.

And when homeowners in Black areas succeeded at getting their applications approved, FEMA awarded them less money on average than applicants in white areas — between 5 percent and 10 percent less, Dr. Raker found.

A 2019 paper by Stephen Billings and Emily Gallagher, at the University of Colorado, found a similar pattern after Hurricane Harvey. Homeowners who lived on blocks with a greater share of nonwhite residents, as well as lower incomes and credit scores, had a lower chance of getting approved for FEMA grants.

“It should be the other way around,” Dr. Gallagher said, noting that more vulnerable populations have an even greater need for federal disaster assistance.

When it comes to money that FEMA reimburses counties and municipalities for rebuilding roads, bridges, hospitals and other facilities after a disaster, racial disparities exist as well.

Counties with a significant share of Black, Hispanic or Native American residents often receive less money from FEMA than mostly white counties, even when suffering the same amount of damage, according to a study published in 2019 by Simone J. Domingue, then a researcher at the University of Colorado, Boulder, who analyzed FEMA grants to 1,621 counties from 2012 through 2015.

Racial disparities also exist in FEMA’s program that purchases and then demolishes damaged homes. Those buyouts are meant to help individual homeowners leave a dangerous location, and reduce future federal costs by avoiding paying for more damage in that spot.

But buyouts can leave people worse off, especially lower-income families who may not have enough money to purchase a home in a safer location. Buyouts can also hurt a community by hollowing it out, making it less attractive while also shrinking the tax base.

In a paper published last year, James R. Elliott, a sociology professor at Rice University, looked at FEMA buyouts around the country from 1990 to 2015. Dr. Elliott and his co-authors found that FEMA “seems to be disproportionately demolishing homes in communities of color,” he said.

The various FEMA programs appear to be making racial inequality worse, sometimes in surprising ways.

Research published in 2018 found that, for white Americans, living in a county hit by a large disaster was a financial boon. Those white residents didn’t just see their wealth grow — it grew five times as much, on average, as the wealth of white residents in counties without major disasters, according to the research by Dr. Elliott and Junia Howell, a sociology professor at the University of Pittsburgh. Wealth in these cases largely referred to changes in home values.

For Black residents of those same disaster-struck counties, by contrast, wealth levels shrank after a disaster, according to the research.

Changes in home values are probably part of the reason, according to the authors: As white neighborhoods receive new federal investment, demand for houses in those neighborhoods goes up, while Black neighborhoods often get less federal spending and so struggle to recover. And Black residents may be more likely to suffer a financial setback, such as losing a home or a job.

“The more aid an area receives from the Federal Emergency Management Agency, the more this inequality grows,” Dr. Howell and Dr. Elliott wrote. “FEMA aid — as currently administered — appears to exacerbate the problem.”

In interviews, researchers said they had no reason to believe FEMA was intentionally discriminating. Rather, the differences may flow from the realities of real estate, municipal finance and the challenges of navigating the federal bureaucracy.

Counties with more nonwhite residents may have less tax revenue, which means fewer staff or resources to navigate the complex process of seeking FEMA grants, or less money to pay the local share that FEMA requires. And houses in Black neighborhoods may have lower property values, which makes them more attractive for government buyout programs with limited funds.

More money to rebuild communities after a disaster may increase property values, pricing out lower-income renters. And individual disaster assistance tends to benefit homeowners more than renters, and people of color are more likely to rent.

The process of seeking FEMA’s help is also demanding, requiring documentation, internet access and time — making it burdensome for those who may be temporarily displaced, whose livelihood may be disrupted, and who may be also struggling to care for children or other family members.

The challenges of navigating that system can be seen in the cases of Mr. Vaussine and Mr. and Mrs. Biagas.

Hurricane Laura sent a pine tree through the roof of the single-story house that Charlotte Biagas grew up in, near a bayou on the north side of Lake Charles. That led to extensive water damage; six weeks later, Hurricane Delta dumped more rain into the home.

Her husband, a 55-year-old Navy veteran, had been working for his brother-in-law’s tiling and flooring business. But the pandemic caused business to dry up, and, with it, his income.

Then the hurricane hit, throwing their lives further into disarray: The couple had to move in with their son, three hours away near Houston. FEMA gave them a trailer to stay in, which remains parked in their driveway. The couple are only now in the process of moving back into their house.

Mr. Biagas described the application process as horrible. “My wife had to submit applications over and over again,” he said. “It was a very trying time.”

A tree also broke through the roof of Mr. Vaussine’s house, knocking out the back wall and destroying his bedroom and bathroom. But in a sense, Mr. Vaussine, an 87-year-old retired oil rig worker, was lucky: His niece, Sharon Moses, was able to handle his application process. Ms. Moses said her uncle has been able to stay with his girlfriend while his house is being repaired. He has yet to move back in.

Keith Turi, FEMA’s assistant administrator for disaster recovery, said in a statement: “Comparing what externally appears to be similar types and amounts of damage is an inaccurate way of evaluating whether a given household received the appropriate level of assistance.”

“If a person believes damages were not accurately captured and included, they can work with our FEMA team to appeal,” Mr. Turi said.

But the appeals process also leaves people of color at a disadvantage, experts said.

The Biagases and Mr. Vaussine appealed to FEMA for more money with the help of SBP, a nonprofit group that helps people cope with the complexity of FEMA programs.

Of the 33 families in and around Lake Charles that SBP has helped appeal their awards, 11 won more money, and the remaining cases are still in process, according to Reese May, the group’s chief strategy and innovation officer. None have been denied.

That success rate suggests that FEMA’s awards are too low, putting the onus on disaster survivors to fight for more, Mr. May said. Appealing is “an arduous process, and one that’s often confusing to the applicant.” Only 3 percent of FEMA applicants file an appeal, the Washington Post reported in April.

The appeals by the Biagases and Mr. Vaussine were both successful, thanks in part to SBP’s help obtaining independent damage estimates. They showed that Mr. Vaussine’s house suffered $60,821 in damage. Mr. and Mrs. Biagas had an almost identical amount of damage, $57,735.

In the end, Mr. and Ms. Biagas received a total of $26,000 from FEMA. Mr. Vaussine got $35,500. In each case, SBP is paying the difference between what FEMA provided and the total cost of repairs, using money raised from donors.

Mr. Biagas said the FEMA staff he dealt with “gave no indication of any kind of racism.” But he said that his neighborhood, which is predominantly African-American, is recovering more slowly than other areas nearby where most of the residents are white.

“We’re still rebuilding, and they’re up and running,” Mr. Biagas said. “I don’t understand it.”