Customs and Border Protection (CBP) discovered 40 tunnels from 2017 to 2021, according to data obtained through a Cato Institute Freedom of Information Act (FOIA) request. CBP discovered these tunnels as former President Trump extended his 30‐​foot wall across hundreds of miles along the border. The former president was warned about the potential for tunnels but insisted that his wall would have anti‐​tunnel “technology.”

The annual figures reveal an interesting jump in tunnel discovery in 2020. As President Trump frantically built out over 300 miles of his border wall in 2020, the agency discovered nearly one new tunnel per month. The 11 tunnels discovered that year were the highest for the period. One of those 2020 tunnels was said to be the “longest ever discovered.” In 2022, one tunnel was found in “one of the most fortified stretches of the border.”