The population of unauthorised immigrants in the United States fell to 10.7 million in 2016, its lowest level since 2004.
It was so, largely due to a decline in the number of people coming from Mexico, the media reported on Wednesday, quoting a study recently released.
The report from the Pew Research Centre, based on U.S. Census data and other figures from 2016, showed the number of illegal immigrants in the United States has declined steadily.
Their numbers were peaked 12.2 million in 2007.
Researchers believe part of the reason for the decline was the economic recession that gripped the United States in 2007.
Thereafter, there was the slow recovery that followed, which limited work opportunities for migrants.
“The combination of economic forces and enforcement priorities may be working together to discourage people from arriving or sending them home,’’ said D’Vera Cohn.
Cohn is one of the authors of the Pew Research Centre report.
President Donald Trump has made immigration enforcement a focus for his administration, most recently, pressing the U.S. Congress to authorise funding of a wall on the border with Mexico.
He has deployed troops in advance of the arrival of a caravan of migrants from Central America.
Even before Trump took office, a decline in the number of illegal immigrants from Mexico had changed the demographic profile of unauthorised migrants in the United States.
Mexico is still the country of origin for about half the unauthorised immigrants in the United States.
But their number in that total population fell by 1.5 million between 2007 and 2016, the Pew report found.
During that decade, the number of unauthorised immigrants from Central America increased by 375,000.
With the share of Mexicans decreasing, Asians account for 22 per cent of unauthorised immigrants, who recently arrived in the United States, the report found.
Among recent arrivals, immigrants in the United States, who overstayed a visa, were likely to outnumber people who illegally crossed the border, it said.
Overall, the Pew study was in line with previous research that found many unauthorised immigrants have been living in the United States for years.
Their children are more likely to have been born in the country than abroad.
Among the 10.7 million unauthorised immigrants, two-thirds of adults have lived in the United States for more than a decade, the Pew Research Centre study found.
Five million U.S.-born children with American citizenship are living with parents or relatives, who are unauthorised immigrants, the study found.