“These are numbers that no immigration system in the world can handle, not even in this country,” acting CBP Commissioner Mark Morgan told reporters at the border in El Paso, Texas.

The increase in arrests coincided with a sharp increase in the number of families crossing the border. A record 473,000 families were apprehended this fiscal year, Morgan said, a more than threefold increase over 2018.

The number of border-crossers peaked in May, when 144,000 people were apprehended or turned away at legal ports of entry. Arrests then dropped over the summer, numbering 40,507 in September.

The volume of border arrests has been unpredictable in recent years. In fiscal year 2017, arrests dropped to a near 50-year low of 303,916, prompting DHS to boast that “the southwest land border is more difficult to illegally cross today than ever before.” But in fiscal year 2018, arrest figures rose to 396,579 before rising much more dramatically in fiscal year 2019.

Border arrests peaked at 1.6 million in 2000 — and remained at or near the 1 million mark until the last two years of George W. Bush’s presidency — before dropping off sharply due to improvements in the Mexican economy and later the Great Recession in the U.S.

The number of total enforcement actions, which include the deportation of people deemed inadmissible under asylum laws, surpassed 1.1 million in 2019, more than double the 2017 figures.

Officials completed 76 miles of new border wall in 2019, Morgan said, adding that he expects 450 new miles of barrier by the end of 2020. The Trump administration has struggled with logistical issues in constructing the wall; The Washington Post reported last week that the government has acquired just 16 percent of the land it needs in Texas.

Timothy Noah contributed to this report.