Not since the 1970s has the number of undocumented immigrants arrested near the U.S.-Mexico border been as low as it was in fiscal year 2011.

Homeland Security recently reported that Border Patrol agents captured 327,577 undocumented immigrants attempting to cross into the U.S. from Mexico. Compare that number to the peak in 2000, when 1.6 million undocumented were caught.

Jeffrey Passel of the Pew Hispanic Center said, “We have reached the point where the balance between Mexicans moving to the United States and those returning to Mexico is essentially zero.”

Though the number of those caught it down, it is not a direct indication of how many are still crossing, as the government is unable to count all of those who cross into the U.S. but are not caught.

Pew also noted that last year, just 150,000 Mexicans moved to the U.S. in 2011, while in 2000, 750,000 Mexicans made America their home.