Securing the borders of the United States has long been a contentious political issue. Although the United States is often described as "a country of immigrants" and a "melting pot," highlighting the relative openness of its borders, the borders have also served as a line of protection against external security threats. Such threats can take many shapes, but in recent years they have mainly included illegal immigration, smuggling and trafficking, and terrorism. With globalization producing increasing transnational threats to the United States, the pressure to use the border as a protection mechanism has grown. Since at least the 1980s, the border has played a central role in the debate over how to provide domestic security in the United States. The terrorist attacks of September 11, 2001 (and subsequent attempts on U.S. soil), the significant domestic population of unauthorized aliens, and recent concerns over drug-trafficking-related violence in Mexico and the potential for spillover into the United States have all continued to fuel this debate. Policymakers have also had to cope with a tension between border protection issues and free market ideals. Market competitiveness and demands for efficiency create a push for more open borders to unencumber the flows of capital and labor. Security concerns, however, frequently impede the movement of goods and labor as they are screened to determine if they pose risks to the United States. Thus, the need for an effective strategy to manage this inherent tension and provide for border protection is ever present. In the past decade, with the reorganization of homeland security and the national security focus on terrorism, several Congresses, Administrations, and The National Commission on Terrorist Attacks Upon the United States (commonly known as the 9/11 Commission) have put forth proposals for how to secure the U.S. border. What has emerged from these efforts has been a generally agreed upon framework of mission and goals. However, while the recent publication of the Quadrennial Homeland Security Review (QHSR) lays the foundation for a cross-agency border protection strategy, some question whether a comprehensive strategy has been sufficiently mapped out. The broad framework currently in place generally consists of a QHSR underpinning supported by a collection of agency or function specific strategic elements that show some commonalities. Thus, the current border protection framework can be summarized as securing and managing the U.S. border through obtaining effective control of the borders, safeguarding lawful trade and travel, and identifying and disrupting transnational criminal organizations. The five strategic commonalities to achieve these goals consist of the Department of Homeland Security (DHS) leadership, deployment of layered security, maximizing domain awareness, promotion of a shared agency culture, and expansion of the border through international and domestic partnerships. For some policymakers, despite the existence of a border protection framework, questions remain as to whether border security officials respond to emerging threats in a sufficiently comprehensive fashion. Moreover, despite the fact that over $100 billion has been appropriated to border protection functions since the formation of DHS, it remains unclear whether border protection measures are being deployed that will ultimately provide for a comprehensive, strategically effective border protection effort without significantly disrupting the border region economy. For congressional policymakers, the current state of border protection presents at least three questions: (1) What does the current border protection framework consist of? (2) Is it working? and (3) Are there more effective alternatives to achieve border protection? The answers to these questions are important for Congress to conduct proper oversight of border protection functions, as well as to gauge its priorities. Moreover, such questions provide an opportunity for legislators to re-evaluate the policies that have been pursued in providing border protection, especially as these policies might impact other elements of the U.S. border, such as markets and communities. This report provides an overview of the current border protection framework and its operationally oriented strategic elements and measures their effectiveness. The report draws on documents from Congress and the Administration, as well as other publications, to pull together an overarching picture of protection at the border. This overview includes a historical background and a definition of what "border protection" means in a contemporary context. Building on this definition, the report provides two theoretical models for border protection approaches based on unilateral and cooperative approaches, followed by an extended analysis of the major elements within the current border protection framework. This analysis also includes discussions of how and why, certain strategic elements notwithstanding, many of the current border-related security policies focus on the physical border rather than conceptualizing the border in broader terms. Statistical analyses of some key indicators are used to evaluate the impact of the current framework. Lastly, this report offers some policy options—both short-term and long-term—for addressing the effectiveness of current border protection policies. It is important to note that while this report deals only with the movement of people, the same principles discussed also apply to the cargo side of border protection. While policymakers have wrestled with notions of what border protection should look like, for border enforcement agencies, the practical questions have remained similar for decades. In essence, border agencies have attempted to develop agency-specific strategies that prevent activities which circumvent U.S. laws on cross-border activities. Although the framework for border protection has evolved, much of the current framework is rooted in traditional enforcement activities and deterrence-based principles as discussed below. For the past 85 years, the United States has attempted to obtain some measure of operational control of its borders. While U.S. government efforts to secure ports of entry (POEs) date back prior to the American Revolution, the founding of the U.S. Border Patrol (USBP) in 1924 by an appropriations act of Congress (Labor Appropriation Act of 1924; 43 Stat. 240) marked the official beginning of efforts to gain complete control of the border. These efforts included the interception of illegal immigrants and the interception of contraband. Fifty years later, under the former Immigration and Naturalization Service (INS) the strategy had evolved to a broader level of abstraction but remained largely similar at its core. According to a Department of Justice (DOJ) report, "[t]he basic tenet of the I&NS [sic] border strategy has been: Given constraints on manpower and resources, attempt to (1) prevent the entry of persons between ports-of-entry, and (2) rapidly interdict and apprehend aliens who have illegally crossed the border." Beginning in the 1980s, political emphasis was placed on reducing the sale of illegal drugs in the United States. Policymakers recognized that much of the drug supply was smuggled across the border in land, air, and maritime environments. This spurred an increased emphasis on gaining operational control to interdict illicit activity. Moreover, this new emphasis lead to a reevaluation of border policies; as a result, border agencies began emphasizing a goal of deterrence (in addition to interdiction). The approach for achieving this deterrence would involve greater manpower and resource deployment to the border regions to monitor activity and engage suspected violators. In 1993, a study commissioned by the Office of National Drug Control Policy concluded that the Southwest border was "being overrun," noting as an example that 6,000 illegal immigrants attempted to enter the United States every night along a 7.5 mile stretch of the San Diego border. The study also concluded that drug smuggling was a serious threat along the Southwest border, and recommended that the INS change its focus from arresting illegal immigrants to preventing their entry. Partly in response to public and congressional concerns about the number of illegal immigrants and drugs entering the country, in 1994 the USBP began implementing its first National Strategic Plan (NSP). Developed as an effort to gain and maintain control of the borders, the original NSP was a multi-phased approach to deploying and focusing USBP resources on areas with the greatest illegal entry of people and goods. The NSP called for a calibrated balance of personnel, aircraft, equipment, technology, and tactical infrastructure. The focus of the NSP was an operational approach known as "Prevention Through Deterrence." The goal was to place USBP agents and resources directly on the border in order to deter the entry of illegal aliens, rather than attempting to arrest aliens after they had already entered the country (this had largely been the prior approach). According to U.S. Customs and Border Protection (CBP), achieving optimum deterrence would mean that increasing the number of agents and resources in a sector would not result in an increase in the number of unauthorized migrants apprehended in that sector. The components of the NSP were ultimately absorbed into a broader "Comprehensive Border Control Strategy" to combat unauthorized immigration, which was released by the Clinton Administration in 1995. This framework outlined a broad new policy emphasizing deterrence to combat unauthorized immigration at the borders, alien smuggling, and visa overstays, thereby making Prevention Through Deterrence the overall border protection policy. The Prevention Through Deterrence policy was embraced by Congress, with both the House and Senate Appropriations Committees in 1996 directing the INS to hire new agents, to reallocate USBP agents stationed in the interior to front-line duty at the border, and to fill the interior office positions with investigative staff. Congressional concern with terrorism and border security rose following a series of terrorist attacks in the 1990s. Starting in 1998, Congress created three commissions to better understand the nature of the terrorist threat facing the nation: the Gilmore Commission, the Bremer Commission, and the Hart-Rudman Commission. The congressional response began with inquiries to the nature of the terrorist threat and the commissioning of several studies, followed by specific, targeted measures to protect the nation following the events of September 11, 2001. The National Commission on Terrorist Attacks Upon the United States, commonly known as the 9/11 Commission, concluded in its final report that funding and completing a "biometric entry-exit screening system" for travelers to and from the United States is essential to national security.