The American Southwest is not the only place grappling with this issue. Around the world, border walls—from India to Eastern Europe—have fragmented habitats and threatened countless species.

The number of apprehensions alog the southwestern U.S. border plummeted by a third during January, according to statistics obtained by ABC News on Tuesday.

The El Paso border sector replaced the San Diego sector as the southwest border's busiest in the month of February, according to the most recent CBP data.

According to the U.S. Army, soldiers won't be arresting people suspected of being in the country illegally, and instead will offer "logistical support" to Border Patrol agents.

The Defense Department is expanding its border role with a new military zone near Yuma, aiming to boost surveillance as crossings continue to fall.

President Trump is breaking with his predecessors’ practice of mostly limiting deployments along the U.S.-Mexico border to small numbers of active-duty soldiers and reservists.

U.S. Customs and Border Patrol said Friday that migrant encounters along the southwest border last month dipped to the lowest level in four years.

In February and March, U.S. Customs and Border Protection averaged 11,363 encounters on the Southwest border. In the final 39 months of the Biden administration, they averaged 186,825.

Illegal crossings at the border with Canada have plummeted since the election -- down 66% from 12,085 people nabbed in November to 4,098 in February -- US Customs and Border Patrol data showed.

EAGLE PASS, Texas — Migrant crossings along the southwest border have seen a historic decline in recent weeks, according to U.S. Border Patrol officials. Milton Moreno, acting chief patrol agent ...