"This is the greatest migration ever from Puerto Rico since records have been taken," said Jorge Duany, a professor of anthropology at Florida International University.
Some reasons for the migration are obvious: Millions of Americans living in Puerto Rico were left without power or running water because of the Category 4 hurricane. Schools were closed. Jobs lost. There seemed to be little hope on the horizon. Puerto Ricans are American citizens and can move to the states without visas or other paperwork. And so, many did.
Yet the scope and shape of this diaspora remain mysterious.
So far, estimates of its size have been based on airline traveler data, which some academics consider unreliable because flying off the island doesn't necessarily mean you're going to migrate. Florida school enrollment numbers have added clarity, but they only cover students who showed up in the Sunshine State, not the entire nation.
To get a clearer picture of the migration patterns, CNN analyzed data from two federal government agencies
obtained under the US Freedom of Information Act.
Together, the data sets from the Federal Emergency Management Agency and the US Postal Service show Puerto Ricans appear to have migrated to all 50 US states in the aftermath of Maria.
As of November 11, FEMA received at least 10,600 applications for disaster assistance from ZIP codes in 50 states and Washington, according to FEMA data provided to CNN.
The applications may represent households, not individual people. The average Puerto Rican household is made up of about three people, according to the US Census Bureau.
In total, FEMA received more than 1 million applications for aid related to Hurricane Maria in Puerto Rico -- indicating nearly everyone who asked FEMA for help under its Individual Assistance programs did not leave the island after the storm.
Still, the data appear to show a substantial increase in the outflow of people from Puerto Rico.
"It sounds possible that we're on pace for a historic net outmigration to the US" from Puerto Rico, said Jens Manuel Krogstad, an editor at the Pew Research Center. "In 2015, the net outmigration was about 64,000 people. And so, from the numbers you described, it sounds like it's possible that even after just a few months we're already on pace to overshoot that."
Separately, between October 1 and December 31, the US Postal Service received at least 6,590 change-of-address requests -- nearly five times the amount received during the same months the previous year -- from Puerto Rico and the US Virgin Islands to the 50 states and District of Columbia. The Postal Service received about 2,900 additional requests to change addresses within Puerto Rico, according to the data, suggesting that while some people left Puerto Rico, others moved within the storm-battered island.
Neither data source is a precise measurement of hurricane-related migration. It's possible that some people changed their addresses for reasons unrelated to Hurricane Maria. FEMA applicants could have listed current addresses in the states for reasons other than migration. They may have listed a relative's address in the states even if they did not move away from Puerto Rico, a FEMA representative said.
Several demographers and disaster experts said these methods of counting -- tracking disaster-assistance claims and official changes of address -- may substantially undercount the true number of people who fled Puerto Rico after Hurricane Maria.
That's because not everyone who leaves Puerto Rico also files a disaster claim with FEMA, and of those who did file and also moved, some may have listed the address of a relative or friend rather than their new location, said Alexis Santos, a Penn State University demographer who grew up in Puerto Rico. Others may move away from the island without knowing exactly where they will land, he said, making it difficult to track relocations based on this paperwork.
Further, people in Puerto Rico are disinclined to use change-of-address forms -- even in normal circumstances, Santos said. He finds it especially unlikely that everyone who moved in the frantic aftermath of Hurricane Maria took the time to file those requests.
"That process -- we normally don't do it," he said. "We use our mom's address or something. Still, my uncles receive letters at my grandmother's house."
"I don't know how representative that is of everyone who's left," William H. Frey, a senior fellow at the Brookings Institution who studied the Hurricane Katrina diaspora, said of the findings. More interesting, he said, is what the data say about where people are going.
Among the surprises: Migrants appear to have moved to every US state.
FEMA applicants listed current ZIP codes in 48 states -- including 11 households in Hawaii, seven in Alaska, three in each of the Dakotas and two in Wyoming.
US Postal Service data suggest people moved after the storm to at least 49 states -- all but Alaska -- plus Washington, D.C., the US Virgin Islands and the Northern Mariana Islands.
"There are people going to South Dakota to work on farms and turkey factories," said Edwin Meléndez, a professor of urban affairs and planning at Hunter College in New York and director of the Center for Puerto Rican Studies. Migrants primarily follow the patterns family members and friends have set before them, he said, but they also seek out steady jobs wherever they might be available.
"People are looking for any kind of job they can get," said the Pew Research Center's Krogstad. "And if (the job is) in Alaska, they're willing to give it a shot.
"That happens a lot with migration," he continued. "It's what happened a lot over the past 25 years with migration to the Midwest (United States) from Latin America -- people moving to small towns that previously had not seen much demographic diversity."
Florida appears to be the top destination for Maria migrants -- by far.
More than half -- 52% -- of households that filed claims with FEMA from the states did so from Florida, which is the closest state to Puerto Rico geographically and has been the top destination for Puerto Ricans in recent years.
Outside Puerto Rico, the top six counties for FEMA claims -- Orange, Osceola, Miami-Dade, Broward, Hillsborough and Polk counties -- all are in Florida, according to the FEMA data. Orlando-Kissimmee-Sanford -- a metro area in central Florida already known as a mecca for Puerto Ricans -- is the top metro area for applicants outside Puerto Rico.
Other top states for migrants were New York, Pennsylvania, Massachusetts, New Jersey, Texas and Connecticut, all of which already had sizable Puerto Rican populations.