Homeland Security, as of last summer, had not performed an analysis of the effectiveness of border fencing and infrastructure, according to a GAO report issued in July, 2018:
“Customs and Border Protection spent approximately $2.3 billion between fiscal years 2007 and 2015 to deploy physical barriers along the nearly 2,000-mile southwest border and, as of March 2018, maintained 654 miles of primary pedestrian and vehicular barriers.
In September 2009, we found that CBP had not assessed the impact of tactical infrastructure—fencing, gates, roads, bridges, lighting, and drainage infrastructure—on border security operations or mission goals. Specifically, we found that CBP had not accounted for the impact of its investment in border fencing and infrastructure on border security. We recommended that CBP conduct an evaluation of the impact of tactical infrastructure on effective control of the border. In February 2017, we found that CBP had not developed metrics that systematically used the data it collected to assess the contributions of border fencing to its mission.”
The GAO report details a succession of Congressional mandates for border security, going back to 1996 (Illegal Immigration Reform and Immigrant Responsibility Act (IIRIRA) of 1996, REAL ID Act of 2005, the Secure Fence Act of 2006, The DHS Appropriations Act of 2008.
“To address these requirements, from fiscal year 2005 through fiscal year 2015, CBP increased the total miles of primary barriers on the southwest border from 119 miles to 654 miles—including 354 miles of primary pedestrian barriers and 300 miles of primary vehicle barriers. CBP used various designs to construct the existing 654 miles of primary fencing. “