According to the new statistics released on Friday, the CBP encountered 188,829 people attempting to come to the US through its southern border in June, a 5 per cent increase from May,in which 180,641 individuals were encountered, reports Xinhua news agency.
The June total is the highest monthly number of encounters by CBP in at least two decades.
June's numbers mean CBP has encountered more than 1 million people so far in the current fiscal year that started October 1, 2020.
The administration of President Joe Biden has been grappling with an increased number of migrants coming into the United States through the southern border.
The Biden administration has undone many of former President Donald Trump's immigration policies, but has kept in place a policy that allows CBP to expel undocumented migrants so as to prevent the spread of the coronavirus at border facilities.
The majority of encounters were from single adults, which totalled 117,602.
The CBP encountered 55,805 family units, 15,253 unaccompanied children and 1,155 accompanied children.
The Biden administration has attributed the increase of migrants to past migratory trends, as well as the Trump administration's hardline immigration policies.
Thirty-four per cent of encounters in June 2021 were individuals who had at least one prior encounter in the previous 12 months, compared to an average one-year re-encounter rate of 14 per cent for Fiscal Years 2014-2019, the CPB said.
CBP Acting Commissioner Troy Miller warned in a statement that amid the summer heat, CBP is seeing a high number of distress calls to CBP "from migrants abandoned in treacherous terrain by smugglers with no regard for human life".
"Although CBP does everything it can to locate and rescue individuals who are lost or distressed, the bottom line is this: the terrain along the border is extreme, the summer heat is severe, and the miles of desert migrants must hike after crossing the border in many areas are unforgiving," Miller said in the statement.