Increased border patrol actually keeps illegal immigrants out?

Apparently that's the case. I know, it's a shocking concept.

SAN LUIS RIO COLORADO, Mexico -- The arrival of U.S. National Guard troops in Arizona has scared off illegal Mexican migrants along the border as a whole, significantly reducing crossings, according to U.S. and Mexican officials.

U.S. authorities said Monday that detentions along the U.S.-Mexico border have decreased by 21 percent, to 26,994, in the first 10 days of June, compared with 34,077 for the same period a year ago.

Along the Arizona border, once the busiest crossing spot, detentions have dropped 23 percent, according to the U.S. Border Patrol.

It's such a novelty. Who'd have thunk it?