Who Is an Undocumented Immigrant?

Answers to common questions about illegal immigration in the United States.

The easy definition of an undocumented immigrant is that he or she is a foreign-born person who doesn’t have a legal right to be or remain in the United States. But that’s where the easy part stops. Let’s look at some common questions and misconceptions about undocumented immigrants.

Is an undocumented immigrant the same as an illegal alien?

Yes, but “illegal alien” is not a technical term–it’s the popularly used jargon, nowhere found in the U.S. immigration laws. Because of its insulting connotations even though it covers a wide variety of types of people, however, we at Nolo prefer to use the more neutral term, “undocumented immigrant.”

How many undocumented immigrants are in the United States?

Estimates from the Department of Homeland Security (DHS) and the Pew Research Center place the number of undocumented immigrants in the U.S. at approximately 11.1 to 11.4 million.

Do all undocumented immigrants sneak across the U.S. border?

Some, but not all. Although accurate numbers are hard to come by, it’s clear that a significant number of undocumented immigrants originally came to the U.S. legally, whether as tourists or on some other nonimmigrant (temporary) visa, and then failed to leave.

Why hasn’t the U.S. deported all undocumented immigrants?

Partly because U.S. enforcement resources are insufficient to keep up with the numbers. One Immigration and Customs Enforcement (ICE) director estimated that it would cost an average of $12,500 to deport each person and according to a 2010 report by the Center for American Progress, it costs $23,480 to deport just one person, including the costs of legal proceedings, apprehension, detention, and transportation.

It’s also important to understand, however, that there are some gray areas, where someone who is undocumented has what almost amounts to a right to remain in the United States. Some undocumented immigrants are unaware that they might have the right to remain in the U.S. based upon old laws, a valid claim for asylum, Temporary Protected Status (TPS), or another form of immigration relief.

For asylum seekers being sought for persecution by their own government who are unable to make direct contact with a refugee agency, the only choice for U.S. entry may be to come illegally. During the time that they are preparing an application for asylum, they have no actual right to be in the U.S.—but then again, if they are caught and placed in removal proceedings, they are allowed to claim asylum at that point, and may very well be approved for asylum (and one year later, be eligible for a green card).

What's more, under a policy called “prosecutorial discretion,” various immigrants, such as students and those with close family members in the U.S., are supposed to be largely left alone by the immigration authorities, so that the authorities can concentrate on immigrants who are criminals or otherwise a risk to U.S. society. Some of these immigrants may actually be granted a sort of limbo status called "deferred action," and in some cases a work permit. See, for example, Deferred Action for Childhood Arrivals (DACA) and Which Undocumented Persons Are Helped by Prosecutorial Discretion.

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