CRS on Border Security

"Drawing on multiple data sources, the report suggests conclusions about the state of border security. Robust investments at the border were not associated with reduced illegal inflows during the 1980s and 1990s, but a range of evidence suggests a substantial drop in illegal inflows in 2007-2011, followed by a slight rise in 2012 and a more dramatic rise in 2013. Enforcement, along with the economic downturn in the United States, likely contributed to the drop in unauthorized migration, though the precise share of the decline attributable to enforcement is unknown.

Enhanced border enforcement also may have contributed to a number of secondary costs and benefits. To the extent that border enforcement successfully deters illegal entries, such enforcement may reduce border-area violence and migrant deaths, protect fragile border ecosystems, and improve the quality of life in border communities. But to the extent that aliens are not deterred, the concentration of enforcement resources on the border may increase border area violence and migrant deaths, encourage unauthorized migrants to find new ways to enter illegally and to remain in the United States for longer periods of time, damage border ecosystems, harm border-area businesses and the quality of life in border communities, and strain U.S. relations with Mexico and Canada." - Border Security: Immigration Enforcement Between Ports of Entry, by Lisa Seghetti, Section Research Manager, December 18, 2014.  (Emphasis added.)