The next explosion of illegal teen border crossing is in full swing, but just one-in-six are being sent home, with most of the rest settled in the United States, according to new government figures.

The U.S. Border Patrol agency reported that they have seized 12,509 illegals under age 18 since October, making it the second biggest surge in history after last year's unprecedented movement of unaccompanied youths across the nation's southern border.

However, when compared to the numbers of illegal kids turned over to U.S. Immigration and Customs Enforcement, it is clear that most are being "booked in" to U.S. facilities and then released — not sent home.

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ICE documents provided to the Washington Examiner shows that ICE is accepting an average of 2,000 a month, meaning that the Border Patrol is returning just one of six kids to their countries, mostly Mexico, Guatemala, El Salvador and Honduras.

For example, the papers show that ICE "booked in" 2,355 unaccompanied youths in December 2014, second only to the previous December's 3,582.

"And this is supposed to be the slow time of year," said expert Jessica M. Vaughan, director of policy studies at the Center for Immigration Studies. "Cities and towns that have already received large numbers of unaccompanied illegal alien minors should brace themselves to repeat the process again in the coming months," she added.

Based on those figures and her experience charting the last year's surge of illegal immigrants, teens, she projected that U.S. border officials are on track seize about 42,000 unaccompanied alien children, or UACs, this year.

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While fewer than the 56,029 taken into the United States last year, it is a clear sign that the administration's claim it has posted a "Return to Sender" note on border crossings isn't having the expected impact on the mostly boys crossing into the United States.

Consider: Already in the current fiscal year, which began in October, ICE has let in 6,580 illegals, more than in all of fiscal year 2011. Generally, said Vaughan, most are released to await an immigration hearing in three to five years.

The "custody management" documents show that babies less than a year old are being accepted into the U.S., with the largest group being 17-year-olds; illegal boys outnumber illegal girls two to one; the top country of origin was Guatemala with 3,292 youths let into the U.S.

The numbers seized at the border are typically higher than the number of those booked into the United States since some are turned back. What's more, only about half of those who try to cross the border illegally are typically caught or even noticed.

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.