The number of illegal immigrants in the United States has grown to as many as 12 million, and they now account for about one in every 20 workers, a new estimate says. Efforts to curb illegal immigration have not slowed the pace, said a report Tuesday by the Pew Hispanic Center. Instead, the report's author said, those efforts are having an unintended consequence: People who illegally enter the United States from Mexico are staying longer because it is harder to move back and forth across the border. "The security has done more to keep people from going back to Mexico...
