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WASHINGTON — The number of undocumented immigrants crossing the southern border last month was the highest total for February in 12 years, according to statistics released by Customs and Border Protection on Tuesday.

In 28 days, and in the same month President Donald Trump declared a national emergency in order to build a border wall, 76,103 immigrants without the needed documentation to enter the U.S. either presented themselves at legal ports of entry or were apprehended by Border Patrol between ports of entry.

It is the highest total for February since 2007, DHS officials said at a press conference Tuesday. It is also the highest single month total since Trump was elected in November 2016. Crossings hit 66,842 in October 2016, just before Trump's election.

Still, February did not set an overall record for border traffic. Before 2008, monthly border crossings were consistently over 100,000, and were higher than 200,000 per month in 2000.

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Customs and Border Protection Commissioner Kevin McAleenan attributed the rise to human smugglers knowing how to exploit loopholes in the American immigration system.

However, previous spikes in border traffic have often preceded crackdowns, such as the uptick that started just before Trump, who had campaigned on getting tough on immigration, was elected and continued till he was inaugurated. The announcement of a government spending deal to build a border wall on Feb. 15 may have precipitated a similar rush, as numbers had been steadily declining over December and January.

The proportion of immigrants crossing illegally by going between ports of entry, rather than presenting themselves at legal ports of entry, also increased in February, making up 87 percent of all undocumented immigrants stopped by CBP.

NBC News previously reported that more immigrants were growing frustrated with long lines to cross the border at legal entry points.

Children traveling unaccompanied as well as families with children made up 65 percent of the crossings in February, up from 61 in January, which CBP officials told reporters is a result of smugglers knowing that children have an easier chance getting through the U.S. immigration system.

The majority of children and families are turning themselves over to U.S. authorities to claim asylum. McAleenan said there was a 120 percent increase in immigrants claiming asylum between fiscal year 2017 and 2018. And so far in fiscal year 2019, which began Oct. 1, there has been a 90 percent increase compared to the previous year.

Border processing facilities were not equipped for children or medical needs of such a vulnerable population, McAleenan said. CBP will add a center in El Paso, Texas, to process families and children.

But, he said, it is only a temporary solution until Congress changes immigration laws.

"The system is well beyond capacity and remains at the breaking point," McAleenan said.