The Trump administration has made the construction of an “impregnable” 2,000-mile wall across the length of the US-Mexico border a centerpiece of its executive orders on immigration and its broader immigration enforcement strategy. This initiative has been broadly criticized based on: Escalating cost projections: an internal Department of Homeland Security (DHS) study recently set the cost at $21.6 billion over three and a half years; Its necessity given the many other enforcement tools — video surveillance, drones, ground sensors, and radar technologies — and Border Patrol personnel, that cover the US-Mexico border: former DHS Secretary Michael Chertoff and other experts have argued that a wall does not add enforcement value except in heavy crossing areas near towns, highways, or other “vanishing points” (Kerwin 2016); Its cost-effectiveness given diminished Border Patrol apprehensions (to roughly one-fourth the level of historic highs) and reduced illegal entries (to roughly one-tenth the 2005 level according to an internal DHS study) (Martinez 2016); Its efficacy as an enforcement tool: between FY 2010 and FY 2015, the current 654-mile pedestrian wall was breached 9,287 times (GAO 2017, 22); Its inability to meet the administration’s goal of securing “operational control” of the border, defined as “the prevention of all unlawful entries to the United States” (White House 2017); Its deleterious impact on bi-national border communities, the environment, and property rights (Heyman 2013); and Opportunity costs in the form of foregone investments in addressing the conditions that drive large-scale migration, as well as in more effective national security and immigration enforcement strategies. The Center for Migration Studies (CMS) has reported on the dramatic decline in the US undocumented population between 2008 and 2014 (Warren 2016). In addition, a growing percentage of border crossers in recent years have originated in the Northern Triangle states of Central America (CBP 2016). These migrants are fleeing pervasive violence, persecution, and poverty, and a large number do not seek to evade arrest, but present themselves to border officials and request political asylum. Many are de facto refugees, not illegal border crossers. This report speaks to another reason to question the necessity and value of a 2,000-mile wall: It does not reflect the reality of how the large majority of persons now become undocumented. It finds that two-thirds of those who arrived in 2014 did not illegally cross a border, but were admitted (after screening) on non-immigrant (temporary) visas, and then overstayed their period of admission or otherwise violated the terms of their visas. Moreover, this trend in increasing percentages of visa overstays will likely continue into the foreseeable future. The report presents information about the mode of arrival of the undocumented population that resided in the United States in 2014. To simplify the presentation, it divides the 2014 population into two groups: overstays and entries without inspection (EWIs). The term overstay, as used in this paper, refers to undocumented residents who entered the United States with valid temporary visas and subsequently established residence without authorization. The term EWI refers to undocumented residents who entered without proper immigration documents across the southern border. The estimates are based primarily on detailed estimates of the undocumented population in 2014 compiled by CMS and estimates of overstays for 2015 derived by DHS. Major findings include the following: In 2014, about 4.5 million US residents, or 42 percent of the total undocumented population, were overstays. Overstays accounted for about two-thirds (66 percent) of those who arrived (i.e., joined the undocumented population) in 2014. Overstays have exceeded EWIs every year since 2007, and 600,000 more overstays than EWIs have arrived since 2007. Mexico is the leading country for both overstays and EWIs; about one- third of undocumented arrivals from Mexico in 2014 were overstays. California has the largest number of overstays (890,000), followed by New York (520,000), Texas (475,000), and Florida (435,000). Two states had 47 percent of the 6.4 million EWIs in 2014: California (1.7 million) and Texas (1.3 million). The percentage of overstays varies widely by state: more than two-thirds of the undocumented who live in Hawaii, Massachusetts, Connecticut, and Pennsylvania are overstays. By contrast, the undocumented population in Kansas, Arkansas, and New Mexico consists of fewer than 25 percent overstays.
The Development of the US National Missile Defense and its Impact on the International Security
