A report released Thursday estimates that more than 2.5 million immigrants in the country illegally live in the metropolitan areas cities of New York, Los Angeles, and Chicago.

All three of these cities have pledged to fight President Trump's plans to expand deportation, and all three are in top 20 metropolitan areas with the most undocumented immigrants in the United States.

The Pew report estimates there are 11.1 million immigrants in the country illegally — or 3.5 per cent of the overall US population.

The study by the nonpartisan Pew Research Center provides a glimpse of where immigrants in the country illegally reside and regions that could be most affected by Trump's crackdown on illegal immigration.

It also highlights the challenges Trump could face in rounding up large numbers of deportees because many areas that are home to large numbers of immigrants lacking legal papers oppose his plans.

A report released Thursday estimates that more than 2.5 million immigrants in the country illegally live in the metropolitan areas cities that have pledged to fight President Trump's plans to expand deportation

A protester locked himself to the van carrying Guadalupe Garcia de Rayos. Apparently fearing her deportation, activists blocked the gates surrounding the office near central Phoenix

Guadalupe Garcia de Rayos is locked in a van that is stopped in the street by protesters outside an Immigration and Customs Enforcement facility in Phoenix, Arizona, on Wednesday. Officials announced that she had been sent back to Mexico on Thursday in a move the city's mayor slammed as a travesty

METRO AREAS WITH THE MOST UNDOCUMENTED IMMIGRANTS - PEW New York - Newark - Jersey City, NY-NJ-PA: 1,150,000 Los Angeles - Long Beach- Anaheim, CA: 1,000,000 Houston - The Woodlands - Sugar Land, TX: 575,000 Dallas - Fort Worth - Arlington, TX: 475,000 Miami-Fort Lauderdale, West Palm Beach, FL: 450,000 Chicago-Naperville-Elgin, IL-IN-WI: 425,000 Washington-Arlington-Alexandria, DC-VA-MD-WV: 400,000 Atlanta-Sandy Springs-Roswell, GA: 250,000 Riverside-San Bernadino-Ontario, CA: 250,000 Phoenix-Mesa-Scottsdale, AZ: 250,000 San Francisco-Oakland-Hayward, CA: 240,000 Boston-Cambridge-Newton, MA-NH: 180,000 San Diego-Carlsbad, CA: 170,000 Las Vegas-Henderson-Paradise, NV: 170,000 Philadelphia-Camden-Wilmington, PA-NJ-DE-MD: 160,000 Seattle-Tacoma-Bellevue, WA: 150,000 Denver-Aurora-Lakewood, CO: 130,000 San Jose- Sunnyvale- Santa Clara, CA: 120,000 Orlando-Kissimee-Sanford, FL 110,000 Austin-Round Rock, TX: 100,000 Advertisement

Any actions by the new administration could be even more widely felt among immigrant communities in regions such as Phoenix, Houston, Dallas and Denver. In these areas, 37 percent of immigrants lack legal status, compared to 26 percent nationwide, the report said.

Immigrants in Phoenix are already starting to see tougher enforcement. A woman in the country illegally who was not targeted for deportation under the Obama administration was taken into custody Wednesday and sent back to Mexico, unleashing protests at a local Immigration and Customs Enforcement office.

In some areas, a larger share of immigrants lack legal papers than others, according to the report by the Washington-based center, which was based on 2014 Census Bureau data.

For example, about 17 percent of immigrants in the San Francisco area lack legal status compared with 35 percent in the region surrounding Las Vegas.

Cities and counties are immersed in a fierce debate over what role, if any, they should play in immigration enforcement as Trump seeks help from local law enforcement to boost deportations and threatens to cut off funding from so-called sanctuary jurisdictions that refuse to assist.

Many large cities including New York, Los Angeles and Chicago have pledged to fight back and not cooperate with requests for assistance from federal deportation agents.

The Pew report looked at large metropolitan areas. Many of the local sanctuary policies cover specific cities within those regions.

About 61 percent of immigrants in the country illegally live in 20 metropolitan areas, the report said.