The enormous number of migrants being encountered at the border has forced Customs and Border Protection (CBP) to add more lines to its chart showing the amount of migrant apprehensions each month -- as arrests rocket past the 200,000 mark.

Homeland Security Secretary Alejandro Mayorkas on Thursday announced that 212,672 migrants were encountered at the southern border in July, a 13% increase over the already massive 188,000 migrant encounters in June. In July 2020, there were just 40,929 encounters.

MAYORKAS ANNOUNCES 212,672 MIGRANT ENCOUNTERS IN JULY, SAYS BORDER ‘IS ONE OF THE TOUGHEST CHALLENGES WE FACE’ 

That is the highest in 21 years and well beyond anything encountered in recent years. On Customs and Border Protection’s Southwest Land Border data center, the start includes data going back to FY 2018 and until recently did not require anything above 150,000 after the 144,116 migrant encounters in May 2019 -- at the peak of that year’s border crisis.

How CBP's Southwest Land Border Encounters chart looked before July's numbers.

How CBP's Southwest Land Border Encounters chart looked before July's numbers. (CBP)

However, it passed the 150,000 mark in March, when the number of encounters shot up from 101,098 in February to 173,283.

Since then however, that number has continued to rise, and in June, there were 188,934 encounters -- yet another high and one that closed in on the ceiling of the graph.

MAYORKAS SAYS BORDER CRISIS ‘UNSUSTAINABLE’ AND ‘WE’RE GOING TO LOSE' IN LEAKED AUDIO 

With Thursday’s announcement, CBP had to add another 50,000 layer to their graph.

How CBP's Southwest Land Border Encounters chart looked before July's numbers.

How CBP's Southwest Land Border Encounters chart looked before July's numbers. (CBP)

In his speech Thursday, Mayorkas emphasized that many of those 212,000 resulted in expulsions under Title 42 public health protections, with 95,788 Title 42 removals. However, that number is lower than in June, when 104,907 migrants were removed under Title 42. He also said that 27% of those encountered had at least one prior encounter in the past 12 months.

Republicans have blamed the Biden administration for the crisis at the border, particularly due to the rollback of Trump-era policies, like the Migrant Protection Protocols (MPP) and the ending of wall construction.

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Mayorkas blamed root causes in Central America like corruption, poverty and violence as well as pointing to the "resurgence" of the American economy "and the gleam of the American promise once again" as a factor. He also conceded that the ending of the Trump-era policies had an effect.

"Another reason is the end of the cruel policies of the past administration and the restoration of the rule of laws of this country that Congress has passed, including our asylum laws that provide humanitarian relief," he said.

He emphasized his commitment to the administration’s plan to open up avenues for asylum while tackling the root causes in Central America and targeting smugglers.

"We have a plan, we are executing our plan and that takes time," he said.

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However, he spoke privately to Border Patrol agents and told them that the situation is "unsustainable."

"A couple of days ago I was down in Mexico, and I said look, you know, if, if our borders are the first line of defense, we're going to lose and this is unsustainable," Mayorkas said, according to leaked audio obtained by Fox News. "We can't continue like this, our people in the field can’t continue and our system isn't built for it."

Fox News' Bill Melugin contributed to this report.