One in ten people in the world (700 million) want to emigrate to another country, according to Gallup. One quarter of potential international migrants (165 million people) say the United States is their desired future residence. Although the desire to move is not the same as intent or action, the poll indicates that the demand for permission to enter the United States each year is high.
Demand outstrips supply for US immigration visas and citizenship, which leads to illegal entry by some. Most migrants who come into the United States without legal approval come from countries that are geographically close, an unfair advantage if they are given precedence over foreigners waiting for visas and green cards. Those pressures call attention to the need for and fairness of border and internal security in the form of physical and identity documentation barriers.
The United States has several responses to individuals overstaying their visas or attempting to enter the country illegally. External border security is handled by US Customs and Border Protection (CBP). Interior enforcement and removal of undocumented immigrants caught at the border are handled by US Immigration and Customs Enforcement (ICE). Legal immigration and naturalizations are handled by US Citizenship and Immigration Services (USCIS).
The number of border security agents has increased dramatically during the last two decades, from 4,000 in 1993, to 10,700 in 2003, and to 21,400 in 2013. The cost in 2013 was about $3.5 billion a year.
Immigrants make the choice to enter the United States illegally based on multiple factors: available alternatives, the payoff for entering successfully, and the probability of being caught. A stronger US economy relative to the Mexican economy (the nationality of 87 percent of border apprehensions) is one reason more people may try to enter the country. The rapid buildup in the number of border security agents during two decades has raised the probability of being caught, lowering the expected value of attempting a crossing.
Border apprehensions have dropped 60 percent in recent years. The US border patrol apprehended nearly a million illegal immigrants per year during the 1990s and the first half of the 2000s. In recent years, the number of apprehensions has fallen to levels not seen since 1970, roughly 400,000 per year. The border patrol attributes the decline to the relative strength of the US and Mexican economies and the rapid increase in the number of border patrol agents.
ICE removed more than 360,000 individuals in fiscal year 2013. About half were found inside the United States, and 82 percent of those had previously been convicted of a crime (mostly for immigration-related offenses).
America is a very large country, and ICE and CBP cannot be expected to apprehend every single individual who enters or remains in the country illegally. One way the US government tries to lower the return to working illegally in the United States is to penalize employers who hire illegal workers. To make it easy for employers to check work status, the United States has a nonmandatory program in place called E-Verify that allows employers to check a worker’s Social Security number against the federal database; once complete, the employer is immune from any federal prosecution if that worker ends up being illegal.
The Pew Hispanic Center estimates that there are almost twelve million illegal immigrants in the United States. In January 2011, DHS estimated that 86 percent of them had been in the country longer than five years, and that 65 percent had been here longer than ten years. Although ICE’s job apprehending illegal immigrants, that so many have been in the country for more than a decade casts doubt on its ability to remove all unauthorized individuals. Lax interior enforcement also explains why individuals continue to attempt to migrate illegally.