President Donald Trump’s immigration enforcement efforts have made a significant impact on border security and arrest numbers over his first 10 months in office, according to Department of Homeland Security data released Tuesday.

The Border Patrol made 310,531 arrests during the fiscal year that ended Sept. 30, a decline of 25 percent from 415,816 a year earlier, according to Customs and Border Protection (CBP). Typically used as a proxy measure for illegal immigration, border arrests fell to their lowest level since 1971.

In the interior of the country, immigration agents carried out 143,470 arrests, an increase of 25 percent from 114,434 a year earlier, according to figures from Immigration and Customs Enforcement (ICE).

The year-end arrest data reflects the administration’s crackdown on illegal immigration, which expanded the number of unauthorized aliens that could be targeted for arrest and deportation. Within a few weeks of taking office, Trump lifted the previous administration’s restrictions on which illegal immigrants would be a high enforcement priority, making anyone in the U.S. illegally a potential subject for deportation.