By Molly Hennessy-Fiske

A new report shows that in recent years, six Western states -- Arizona, California, Colorado, Nevada, New Mexico and Oregon -- saw declines in "unauthorized immigrants" entering the country illegally.

Seven states -- five of them in the East -- saw increases in the number of immigrants residing in the country illegally: Florida, Maryland, New Jersey, Pennsylvania, Virginia, Idaho and Nebraska.

The report, released Tuesday by the Pew Research Center's Hispanic Trends Project, is based on estimated "unauthorized immigrant" populations in 2012 compared with 2009, using U.S. Census Bureau data.

It also tracked the population over time, finding the national population of such immigrants basically unchanged in recent years but some state numbers changing significantly.

Other states with decreases during the period are in the South (Alabama, Georgia and Kentucky), the Midwest (Illinois, Indiana and Kansas) and the Northeast (Massachusetts and New York).

Researchers found that the population of "unauthorized immigrants" grew dramatically from 1990 to 2007 but has since slowed, with growth flat from 2009 to 2012, leaving a total of more than 11 million nationwide.

The recent decreases were mostly due to a drop in the number of such immigrants arriving from Mexico, the Pew analysis found. The exception was Massachusetts, where the decrease was due to a decline in the number of immigrants from other countries.

Tuesday's report comes as national leaders prepare to address immigration policy in Washington. President Obama is expected to issue an executive order soon that could shield as many as 5 million immigrants from deportation. But Republicans, who will control both houses of Congress come January, have demanded that the president wait for them to weigh in on the issue.

Among the groups widely thought to be under consideration for relief from deportation under the president's plan are longtime U.S. residents with U.S.-born children.

The Pew Research Center estimates that in 2012, there were 4 million "unauthorized immigrant" parents living in the U.S. with American-born children (either minors or adults). Of those, 3 million had lived in the U.S. for 10 years or more.

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