U.S. Customs and Border Protection (CBP) officers apprehended more than 46,000 illegal immigrants along the southwest border last month, according to the Department of Homeland Security (DHS).

That marks a 16.4 percent increase over July and comes after two straight decreases. Since 2012, only in 2016 have August border crossings exceeded the 46,560 apprehensions assessed last month.

Experts closely track border apprehensions to measure illegal immigration from Mexico, with a general estimate of one successful crossing for every one that immigration officials stop.

A DHS spokesman, Tyler Houlton, pointed the finger at a failure to close loopholes that lure migrants.

“August Southwest Border Migration numbers show a clear indicator that the migration flows are responding to gaps in our nation’s legal framework,” he said in a statement. “While the overall numbers are consistent with an expected seasonal increase, the number of family units along the Southwest border increased 38 percent – 3,500 more than July and the highest August on record.”

The 46,560 apprehensions consist of 37,544 caught near the border and another 9,016 deemed inadmissible at border crossing stations. With one more month to go in fiscal year 2018, the 469,192 total already has blown away the 303,916 recorded in fiscal year 2017 and is on track to be the most in the past seven years.

Children and adults traveling with children accounted for 46 percent of all illegal immigrants arrested between the ports of entry last month. That share has risen steadily through the fiscal year. Last October, for instance, children and so-called family units made up a mere 31 percent of the total.

Because of court rulings prohibiting the long-term detention of parents and children together — and outrage that prompted President Donald Trump to end a practice of separating illegal immigrant families — U.S. authorities generally release adults and children traveling together and hope they will show up for immigration court hearings months or years in the future.

Through the third quarter of the current fiscal year, Houlton noted, only 1.4 percent of those family members were from El Salvador, Guatemala, Honduras and other noncontiguous countries. Deportation of children and families is more complicated if the illegal immigrants are not from Mexico or Canada.

“Smugglers and traffickers understand our broken immigration laws better than most and know that, if a family unit illegally enters the U.S., they are likely to be released into the interior,” Houlton said in his statement. “Specifically, DHS is required to release families entering the country illegally within 20 days of apprehension.”

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Jessica Vaughan, director of policy studies at the Center for Immigration Studies, agreed. She said adults caught alone face immediate consequences for crossing the border illegally. Families do not, she said.

“It’s clear that people have realized the way to come is with a family or with kids,” she said. “The catch-and-release policies are continuing to attract thousands of people every month … The only way to deter people is for them to think they are going to be sent home quickly.”

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Vaughan, whose think tank favors stricter immigration enforcement, said men who would have come by themselves in earlier years to work in the United States now are bringing their families. Or they are sending their wives and children separately, she said.

“It’s really troubling, because this is such a dangerous thing for people to do,” she said.

But Vaughan said Central Americans know that their children represent the best chance of being allowed to stay. She compared the strategy to a tennis player taking the highest-percentage shot to win a point.

“In the case of these parents, the highest-percentage shot is to take or send their kids,” she said.