Is there definitive evidence that the Trump Administration’s expanded border wall has deterred illegal immigration?
It’s hard to measure the impact of the Trump administration's expanded border wall on immigration patterns. Most of the added wall was only built this year and, according to a 2017 government audit, authorities lack metrics to measure its efficacy. Furthermore, it’s difficult to isolate the wall’s effect from other recent factors such as the lagging U.S. economy and movement restrictions brought on by the coronavirus.
While Department of Homeland Security data show that "illegal border crossings have decreased in areas where barriers are deployed,” overall numbers remain high. Apprehensions of undocumented entrants did fall in fiscal year 2020 (401,651) from 2019 (851,508) but remained higher than in 2017 (303,916) and 2018 (396,579). After hitting an April low, crossings are again on the rise with increases of 9% in September and 35% in October relative to last year's monthly totals.