Publication Date



The unauthorized immigrant (illegal alien) population in the United States is a key and controversial immigration issue. Competing views on how to address this population have been, and continue to be, a major obstacle to enacting immigration reform legislation.

It is unknown, at any point in time, how many unauthorized aliens are in the United States; what countries they are from; when they came to the United States; where they are living; and what their demographic, family, and other characteristics are. Demographers develop estimates about unauthorized aliens using available survey data on the U.S. foreign-born population and other methods. These estimates can help inform possible policy options to address the unauthorized alien population. Both the Department of Homeland Security (DHS) and the Pew Research Center estimate that approximately 11.5 million unauthorized aliens were living in the United States in January 2011. DHS further estimates that there were some 11.4 unauthorized residents in January 2012. Pew has released a preliminary estimate of 11.7 million for the March 2012 unauthorized resident population.

The Immigration and Nationality Act (INA) and other federal laws place various restrictions on unauthorized aliens. In general, they have no legal right to live or work in the United States and are subject to removal from the country. At the same time, the INA provides limited avenues for certain unauthorized aliens to obtain legal permanent residence.

Over the years, a range of options has been offered for addressing the unauthorized resident population. In most cases, the ultimate goal is to reduce the number of aliens in the United States who lack legal status. One set of options centers on requiring or encouraging unauthorized immigrants to depart the country. Those who support this approach argue that these aliens are in the United States in violation of the law and that their presence variously threatens social order, national security, and economic prosperity. One departure strategy is to locate and deport unauthorized aliens from the United States. Another departure strategy, known as attrition through enforcement, seeks to significantly reduce the size of the unauthorized population by across-the- board enforcement of immigration laws.

One of the basic tenets of the departure approach is that unauthorized immigrants in the United States should not be granted benefits. An opposing strategy would grant qualifying unauthorized residents various benefits, including an opportunity to obtain legal status. Supporters of this type of approach do not characterize unauthorized immigrants in the United States as lawbreakers, but rather as contributors to the economy and society at large. A variety of proposals have been put forth over the years to grant some type of legal status to some portion of the unauthorized population. Some of these options would use existing mechanisms under immigration law to grant legal status. Others would establish new legalization programs. Some would benefit a particular subset of the unauthorized population, such as students or agricultural workers, while others would make relief available more broadly.


Suggested Citation
Bruno, A. (2014). Unauthorized aliens in the United States: Policy discussion . Washington, DC: Congressional Research Service.