“Some of these areas could be affected by the Trump administration’s promise to take action against localities that do not cooperate with federal officials in identifying unauthorized immigrants,” the report said.

The report, the center’s first look at undocumented immigrant populations at the metro level, highlights areas that could see pronounced effects from President Trump’s efforts to crack down on illegal immigration.

An estimated 180,000 residents of Greater Boston are in the country illegally, a population that ranks as the 12th highest among metropolitan areas nationwide, according to a new report from the Pew Research Center.

The report, based on figures for 2014, found that the United States’ undocumented immigrant population — like the population of immigrants in the country legally — is highly concentrated in metropolitan centers, more so than the nation’s overall population.


The 20 areas with the most undocumented immigrants are home to a combined 6.8 million undocumented immigrants, or about 61 percent of the total number of undocumented immigrants nationwide.

Among immigrants in the country legally, 65 percent live in those same metro areas, the report said.

Yet those areas account for only about 36 percent of the country’s total population.

Metropolitan areas around New York City and Los Angeles had by far the largest undocumented immigrant populations nationwide with estimates of 1.15 million and 1 million, respectively. The next-highest total was 575,000 in the Houston metro area.

Undocumented immigrants in metro Houston accounted for about 8.7 percent of the overall population, the highest such percentage of the top 20 metro areas. Next were Las Vegas (8 percent) and Los Angeles (7.5 percent).

Nationally, there are 11.1 million undocumented immigrants, who make up about 3.5 percent of the total population, the report said.

The undocumented immigrant population in Greater Boston accounts for about 3.7 percent of the total population of more than 4.5 million people within the metropolitan area, which includes a wide swath of Eastern Massachusetts and parts of New Hampshire, the report found.


Greater Boston is the 10th largest metro area nationally and its undocumented immigrant population is the 12th largest, the report said.

The city of Boston alone is home to an estimated 35,000 undocumented immigrants, or about 5.5 percent of the city’s total population, according to the report.

In his first days in office, President Trump issued executive orders to expand deportations of undocumented immigrants and to strip federal funding from so-called sanctuary cities.

The orders have faced significant resistance.

Mayors of some major sanctuary cities — including ones that are at the center of metro areas home to large numbers of undocumented immigrants — have vowed to not change their policies in the wake of Trump’s orders to aggressively pursue undocumented immigrants.

Such cities include Boston, New York City, Los Angeles, Chicago, San Francisco, Seattle, and Austin, Texas.

And all but three of the top 20 metro areas identified by the Pew report voted for Democrat Hillary Clinton in November’s presidential election, and many voted for her by a wide margin, according to a review by the statistics-focused news website FiveThirtyEight.

In recent days, reports have swirled that federal immigration authorities have been rounding up large numbers of people in communities around the country, though it was unclear how those efforts might be connected to Trump’s call to step up immigration enforcement. The Associated Press reported Friday that the president is considering mobilizing as many as 100,000 National Guard troops to round up undocumented immigrants. The White House quickly denied the report.


The latest Pew analysis marked the first time it had released estimates of undocumented immigrants at the metro-level.

But the center had previously published other estimates of undocumented immigrants, including state-level figures, which showed that an estimated 210,000 undocumented immigrants live in Massachusetts.

The table below shows more state-level estimates.

Matt Rocheleau can be reached at matthew.rocheleau@globe.com. Follow him on Twitter @mrochele.