With respect to border enforcement outputs, available data indicate that the southwest land border is more difficult to illegally cross today than ever before. First, survey data, mathematical models, and USBP assessments suggest that a growing share of attempting crossers between POEs are apprehended or interdicted: 55 to 85 percent today (depending on the specific estimate), versus 35 to 70 percent a decade ago. Second, administrative and survey data suggest that a much higher share of unlawful immigrants are deterred from making a subsequent attempt after being repatriated: about 55 to 75 percent today versus 10 to 40 percent a decade or two ago. Third, survey data and USBP assessments indicate that almost all illegal border crossers resort to hiring a smuggler today, versus just over half 30 years ago. Meanwhile, average smuggler fees have increased from a few hundred dollars in the 1980s to almost $4,000 today, accounting for inflation.
With respect to border enforcement outcomes, available data also indicate the lowest number of illegal entries at least since 2000, and likely since the early 1970s. First, the U.S. Border Patrol made 408,000 southwest border apprehensions in 2016, the fourth-lowest number since 1972, and a 75 percent drop from 1.6 million apprehensions in 2000. The drop in apprehensions likely understates the drop in illegal entries given the apparent increase in the apprehension rate. Second, USBP’s observation-based estimate of known got aways fell 83 percent between 2006 and 2016, from 615,000 to 106,000, in spite of improved detection capacity. Third, the IDA Corporation estimates that successful illegal entries fell 91 percent between 2000 and 2016 (from 1.8 million to 170,000), though DHS is still working to validate and refine IDA’s methodology.