Border cops encountered more than 76,000 people they say tried to illegally cross from Mexico into the U.S. in February, making it the highest level of illegal immigration the U.S. has seen in one month since 2007.

The number shot up from 58,000 who were arrested and turned away at ports in January. The monthly rate has slowly crept up from 17,000 during President Trump's third month in office in 2017.

Senior Homeland Security officials said Tuesday they expect the number of migrants illegally entering the U.S. from Mexico to continue spiking due to a continued surge of family and children arriving daily.

"It's well-known at this time that adults with children will not be detained during the immigration proceedings for illegal entry. The word of mouth and social media quickly gets back to those in the Northern Triangle countries, that if you bring a child, you'll be successful," a senior Border Patrol official told reporters.

"Without a consequence, without being able to deliver a consequence to these individuals for illegally crossing our borders, the Border Patrol has no reason to expect this trend will decrease. In fact, we expect this trend will increase," the official said.

A total 396,000 people were arrested at the southwest border in 2018, 157,000 of whom were from those two groups.

The number of children traveling with parents topped 50,000 in 2018 — up 20 percent from 41,000 a year earlier.

The number of people who traveled in family units shot up 42 percent from 75,000 in 2017 to 107,000 last year.

Both of those categories have continued to creep up since fiscal 2019 started last October.

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Half of the 50,000 people arrested at the southern border in January for illegally crossing into the U.S. were families. If that trend continues through 2019, it will tick up to around 300,000 family units by September.

The most families and unaccompanied children arrived in the Rio Grande Valley Sector of Texas, Yuma Sector of Arizona, and El Paso Sector of Texas, though it includes New Mexico.

One of the main reasons the number has crept up is because families and children are being trafficked in large groups by smugglers.

Instead of a handful or a dozen people arriving or illegally crossing near a port of entry, 100 people or more are showing up at a time.

Since October, CBP has documented 70 large groups of more than 100 people each. A total of 12,000 people who arrived in large groups have been taken into custody in the first five months of fiscal 2019.

The families and minors are also making up a larger portion of all apprehensions. In 2019, they have accounted for 60 percent of arrests.