The number of migrants apprehended at the southern U.S. border slid for the sixth straight month in November, according to data released Monday by U.S. Customs and Border Patrol.

Some 33,500 migrants were taken into custody by immigration officials last month, a 2,000-person decrease from October and the latest in a downward trend that has continued since apprehensions peaked in May at the highest levels seen in over a decade.

In addition to those apprehended at the border, about 9,100 migrants were deemed inadmissible last month after presenting themselves lawfully at ports of entry, bringing the total number of migrants facing enforcement action to 42,649 last month.

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The Trump administration has continued its aggressive campaign to decrease the number of migrants – including those seeking asylum – arriving at the southern border.

Officials credit a number of policy initiatives for the decline in migrant apprehensions since May, including partnerships with Mexico and the three Central American countries known as the Northern Triangle.

The administration in recent months struck controversial asylum deals with Honduras, Guatemala and El Salvador that would allow the U.S. to send asylum-seekers back to those countries to seek asylum there instead. The pact with Guatemala took effect last month, and the administration began sending migrants from the U.S. to Guatemala under the deal.

The deals have been widely panned by immigration advocates and others who argue that the countries are unsafe. The region struggles with crime and poverty, and migrants have fled the area in droves in the last several years.