"In May, 132,887 people were apprehended between ports of entry on the Southwest Border, compared with 99,304 in the month of April and 92,840 in March", the Customs and Border Protection.
May apprehensions marked the highest monthly total in 13 years, Customs and Border Protection officials said. The total included 84,542 family units and 11,507 unaccompanied minors.
The numbers were released shortly before a meeting between Vice President Mike Pence and Mexican Foreign Secretary Marcelo Ebrard to discuss Mexico's role in halting the migration.
President Donald Trump is threatening to impose a 5 percent duty on all Mexican imports unless the government halts the flow of migrants, most from the Central American nations of El Salvador, Guatemala and Honduras.
US law requires family units and unaccompanied minors who cross the border illegally and ask for political asylum to be released in the United States while their cases are processed by overburdened immigration courts — a process that can take years.