The number of immigrants living in the U.S. illegally is at its lowest in more than a decade and, for the first time in years, has probably dropped below 11 million.
A new study by the Center for Migration Studies estimates that 10.9 million immigrants are living in the country without authorization. That is the lowest level since 2003 and the first time the number has dipped below 11 million since 2004.
The decline, which has been documented by previous studies as well, runs counter to the widespread image on the Republican presidential campaign trail of a rise in illegal immigration.
GOP front-runner Donald Trump has said illegal immigration rates are "beyond belief" and has claimed that immigrants bringing crime and disease are "just pouring across the border." Trump has pledged mass deportations and a giant border wall, while criticizing as weak his more moderate rivals, including Jeb Bush, who has proposed giving immigrants already in the country a path to legal status.
According to the report, written by a prominent former government demographics expert, illegal immigration has dropped steadily since 2008, driven in part by a large number of immigrants from Mexico returning home.
Since 2010, the number of Mexicans living in the U.S. illegally declined by about 612,000, or 9%, the report says.
The population of such Mexicans in California shrunk by about 250,000 from 2010 to 2014, the study found. The state's total population of immigrants here illegally fell by 318,000 during that time.
Although the study found declines in the number of such immigrants from South America, the Caribbean and Europe, it reported an increase in the number of immigrants crossing illegally from Central America, which has been gripped with rising violence in recent years.
Manuel Pastor, a sociology professor at USC, said the decline in the numbers of immigrants living in the country illegally can be linked to a decline in the U.S. economy and other factors. For example, lower birthrates in Mexico mean there is less competition for jobs there and less pressure to head north to find work.
Pastor said Trump's heated rhetoric about the growing threat of illegal immigration is "detached from reality" and partly the product of a presidential primary system in which Republican candidates must appeal to their party's most conservative -- and mostly white -- voters.
Pastor cited "growing demographic anxieties" among white Americans about the country's rapidly changing racial and ethnic makeup, and said Trump's anti-immigrant rhetoric plays into that.
"This is a very racialized debate," he said.
For more immigration news, follow me on Twitter: @katelinthicum