From the Summary: "Congress has repeatedly shown interest in examining and expanding the barriers being deployed along the U.S. international land border. The United States Border Patrol (USBP) deploys fencing, which aims to impede the illegal entry of individuals, and vehicle barriers, which aim to impede the illegal entry of vehicles (but not individuals) along the border. The USBP first began erecting physical barriers in 1990 to deter illegal entries and drug smuggling in its San Diego sector. The ensuing 14-mile-long San Diego 'primary fence' formed part of the USBP's 'Prevention Through Deterrence' strategy, which called for reducing unauthorized migration by placing agents and resources directly on the border along population centers in order to deter would-be migrants from entering the country. [...] In addition to border fencing, the USBP deploys both permanent and temporary vehicle barriers to the border. Temporary vehicle barriers are typically chained together and can be moved to different locations at the USBP's discretion. Permanent vehicle barriers are embedded in the ground and are meant to remain in one location. A number of policy issues concerning border barriers generally and fencing specifically may be of interest to Congress, including, but not limited, to their effectiveness, costs versus benefits, location, design, environmental impact, potential diplomatic ramifications, and the costs of acquiring the land needed for construction. This report will be updated as circumstances warrant."
CRS Report for Congress, RL33659