The U.S. Department of Homeland Security (DHS) is responsible for securing and managing the nation's borders. Over the past decade, DHS has dramatically stepped up its enforcement efforts at the U.S.-Mexico border, increasing the number of U.S. Border patrol (USBP) agents, expanding the deployment of technological assets, and implementing a variety of "consequence programs" intended to deter illegal immigration. During this same period, there has also been a sharp decline in the number of unauthorized migrants apprehended at the border. Trends in total apprehensions do not, however, by themselves speak to the effectiveness of DHS's investments in immigration enforcement. In particular, to evaluate whether heightened enforcement efforts have contributed to reducing the flow of undocumented migrants, it is critical to estimate the number of border-crossing attempts during the same period for which apprehensions data are available. With these issues in mind, DHS charged the National Research Council (NRC) with providing guidance on the use of surveys and other methodologies to estimate the number of unauthorized crossings at the U.S.-Mexico border, preferably by geographic region and on a quarterly basis. Options for Estimating Illegal Entries at the U.S.-Mexico Border focuses on Mexican migrants since Mexican nationals account for the vast majority (around 90 percent) of attempted unauthorized border crossings across the U.S.-Mexico border.

The U.S. Department of Homeland Security (DHS) is responsible for securing and managing the nation's borders. Over the past decade, DHS has dramatically stepped up its enforcement efforts at the U.S.-Mexico border, increasing the number of U.S. Border patrol (USBP) agents, expanding the deployment of technological assets, and implementing a variety of "consequence programs" intended to deter illegal immigration. During this same period, there has also been a sharp decline in the number of unauthorized migrants apprehended at the border. Trends in total apprehensions do not, however, by themselves speak to the effectiveness of DHS's investments in immigration enforcement. In particular, to evaluate whether heightened enforcement efforts have contributed to reducing the flow of undocumented migrants, it is critical to estimate the number of border-crossing attempts during the same period for which apprehensions data are available. With these issues in mind, DHS charged the National Research Council (NRC) with providing guidance on the use of surveys and other methodologies to estimate the number of unauthorized crossings at the U.S.-Mexico border, preferably by geographic region and on a quarterly basis. Options for Estimating Illegal Entries at the U.S.-Mexico Border focuses on Mexican migrants since Mexican nationals account for the vast majority (around 90 percent) of attempted unauthorized border crossings across the U.S.-Mexico border.

The U.S. Department of Homeland Security is responsible for controlling the flow of goods and people across the U.S. border, but compelling methods for producing estimates of the total flow of illicit goods or border crossings do not yet exist. This paper describes four innovative approaches to estimating the total flow of illicit border crossings between ports of entry. Each approach is sufficiently promising to warrant further attention.

The authors examine U.S. efforts to prevent illegal immigration to the United States. Although the United States has witnessed a sharp drop in illegal border crossings in the past decade alongside an enormous increase in government activities to prevent illegal immigration, there remains little understanding of the role enforcement has played. Better data and analyses to assist lawmakers in crafting more successful policies and to support administration officials in implementing these policies are long overdue.

This report presents initial findings from a scoping study titled “Economic Value of Human Smuggling to Transnational Criminal Organizations.” A primary goal of this study, which was completed in less than two months, was to develop a preliminary estimate of transnational criminal organizations’ (TCOs’) revenues from smuggling migrants from the Northern Triangle region of Central America—consisting of Guatemala, Honduras, and El Salvador—to the United States. In addition, we sought to establish what is known or knowable about the characteristics, including the structure, operations, and financing, of TCOs that engage in human smuggling along those routes.