"one of an estimated 300,000 children of illegal immigrants born in the United States every year, according to the Pew Hispanic Center. They're given instant citizenship because they are born on U.S. soil, which makes it easier for their parents to become U.S. citizens.
That's because those babies can eventually sponsor their parents - when they turn 21 years old. "
story
"As of 2003, the US Citizenship and Immigration Services put the number at 7 million. Since then, United States immigration officials have said the number has grown by as much as 500,000 a year.
Those closest to the fight to protect US borders say the figure is higher. The US Border Patrol union Local 2544 in Tucson, Ariz., says the total number of illegal immigrants in the US today is between 12 million and 15 million."
story
So, yep, looks like well over half have "anchor babies"