How many migrants have arrived in Massachusetts? It’s hard to know for sure, but they keep coming.

A Globe review indicates a dramatic increase in migrants from the start of the current immigration wave

Migrants staying in an overflow shelter in Cambridge spent the day at La Colaborativa in Chelsea.Erin Clark/Globe Staff

For nearly two consecutive years, a rising stream of migrants — many pregnant or with children by their side — have arrived in Massachusetts, fleeing violence and poverty in search of housing, food, and security. The influx has put pressure on state officials who have scrambled to support the emergency assistance shelter program, which they estimate will cost a whopping $915 million in the next fiscal year.

As the state figures out how to cover the cost, there’s a key figure that officials don’t know for sure: how many migrants are actually arriving.

Governor Maura Healey’s administration gets its data from Massachusetts-based resettlement agencies, a network of organizations that help new arrivals with basic needs and report those eligible for federal services to the state. Through that process, the administration has logged more than 11,000 migrants from October 2022 through September 2023, the federal fiscal year.

That represents an increase of more than 152 percent over the previous fiscal year, when the state received reports of 4,359 migrants from the agencies. But it’s still “not a comprehensive count” of the total number of new arrivals pouring into the state, said Olivia James, a spokesperson for the Department of Health and Human Services.

The state, she said, can only count the new arrivals who receive federal services in Massachusetts. That group includes resettled refugees who have lived in the United States for a significant period of time and some Haitian and Cuban migrants whom the Biden administration deemed eligible for benefits such as Medicaid and cash assistance after fleeing life-threatening or other urgent situations. According to the state, 72 percent of migrants counted in state figures were from Haiti, 13 percent were Ukraine, 5 percent were Afghan or Syrian, and 10 percent were refugees from other countries.

The state’s count does not include immigrants who don’t qualify for certain categories of legal status and thus aren’t eligible for federal services, such as people who overstay tourist visas or illegally cross into the United States. Those individuals, however, often show up at food pantries, day shelters, and other programs dedicated to helping new arrivals find their footing, say the nonprofit workers at the front lines of the state’s migrant crisis.

“Not every person who comes here without documents goes through resettlement agencies,” said Gladys Vega, executive director of La Colaborativa, a Chelsea nonprofit that is not a resettlement agency but serves hundreds of new immigrants every year with donated food, language classes, and free legal aid.

The gap in the state’s count raises questions about whether policymakers and nonprofits have the data necessary to fully understand and plan for the scope of the need. It also reveals how much the migrant wave has swelled in just a year, creating a crisis thousands of miles from the US-Mexico border.

On any given day, the waiting room at Immigrant Family Services Institute in Mattapan — decorated with a garland made up of miniature flags from around the world — is packed with Haitian migrants. Outside, families wait for their turn to meet with a staff member who will connect them with housing and donated goods, such as strollers, winter jackets, and backpacks.

Leaders there say the nonprofit has received more than 9,400 newly arrived migrants in fiscal year 2023. The vast majority of them are Haitian.

And the director of a nonprofit in Chelsea, which doubles as a day shelter for hundreds, said her group has helped more than 1,000 Latin American migrants who have reached Massachusetts this year.

Internal figures from one nonprofit Massachusetts resettlement agency, the Boston-based International Institute of New England, show the group helped 10,047 people from 49 countries in fiscal year 2023, which could include some migrants served by other agencies.

The last two years have been difficult, La Colaborativa’s Vega said, as the pace of new arrivals has continued to accelerate. Some weeks there are 30 newcomers who seek help at La Colaborativa; other weeks there are closer to 70.

In 2022, then-governor Charlie Baker’s administration reported the state had served 4,000 migrants in the fiscal year 2022. But that count excluded thousands of migrants served by other types of nonprofits that are not resettlement agencies, such as faith-based groups or local food pantries.

Jeff Thielman, who heads the International Institute of New England, said the waitlist for an appointment at his agency to get enrolled in services now extends to May, meaning there are hundreds of new, potentially eligible arrivals who have yet to be added to the state’s database.

That means fewer people are reported by state officials to the federal government, which could affect how much money is funneled toward agencies like his, Thielman said.

For months, Healey and other state leaders, have been working to manage the influx of migrants fleeing turmoil and poverty in Haiti, Central and South America, and beyond. They often come in need of medical assistance and help navigating the complex immigration system. And coupled with a housing crisis, it’s nearly impossible for many new arrivals to find affordable shelter.

In August, Healey appealed to the federal government for help as she announced an emergency declaration aimed at addressing the state’s overburdened shelter system. She has twice written to the Biden administration, imploring officials to quickly grant work permits to the thousands of migrants who have overwhelmed the state’s shelter system and to send money to help the state provide necessary resources such as housing and transportation.

In the meantime, the state has poured hundreds of millions of dollars into the emergency shelter system, among other investments. It awarded a $5 million grant to the United Way to partner with other nonprofits and open overflow shelters for families awaiting a slot in the shelter system, paid back thousands to schools who have absorbed migrants into their student populations, and created a brand-new legal services program to help migrants put together asylum applications so that they can eventually obtain permits to work.

The challenge the state faces is not unique.

In January, Healey was among nine governors who called on federal officials to fix the country’s immigration system, urging leaders from both major political parties “to work together to solve what has become a humanitarian crisis.”

Even the federal government does not keep complete records of where migrants go after they are released from custody at the border.

When migrants arrive at the US-Mexico border seeking asylum from countries rife with political or economic unrest, those not immediately turned away often turn themselves in to federal authorities and receive a “notice to appear” in front of an immigration judge at a future date.

As these new arrivals disperse across the country, state and local governments end up with the burden of caring for them — and keeping track of how many are there.

Thielman, whose staff has been crushed with work for the last year-plus, said more help from the federal government is crucial to keep up with the need. But that will require a more accurate picture of what the state is facing.

“Money from the federal government is not coming to people living in the Commonwealth fast enough,” he said. “The money isn’t coming to the state, but [migrants] are looking out for more state assistance. That puts the pressure on everyone else to help them out.”