How did Illegal Aliens Arrive: Without Inspection or With Visas?

Illegal aliens are divided into two categories; those who crossed the border illegally and those who entered with visas as nonimmigrants and stayed illegally. Those who came across the border illegally are classified as EWIs (Entered Without Inspection). Various estimates exist as to what share of the illegal aliens are EWIs versus overstayers. Advocates for illegal aliens tend to exaggerate the share of illegal aliens who arrived with visas. They do so in the apparent belief that this will lessen the public's apprehension that our borders are out of control and to minimize concern about aliens who have not been screened for criminal records, terrorist connections, or contagious diseases.

Wikipedia's entry on "Illegal Immigration to the United States" states, " This mode of entry [EWI] accounts for 6 to 7 million people, slightly more than half of the total population."1 That assessment is attributed to the Pew Hispanic Center and a report issued in May 2006.2 In 1996, Robert Warren, the director of the immigration statistics office of the Immigration and Naturalization Service (INS), issued a report that estimated that, "41 percent, of the total undocumented population in 1996 are nonimmigrant overstays."3 That put the EWI population at about three-fifths of about 5 million illegal aliens. The U.S. General Accounting Office (GAO) looked at the estimation method of INS and concluded in 1995 that, "...we found overstay estimates that are, on average, lower than corresponding INS estimates. Specifically, our estimates are between 16 percent and 47 percent lower than INS'. "4

It should be understood, however, that the estimates by Warren and others are just that, i.e., estimates. Just as there are varying estimates of the size of the illegal alien population, there are varying estimates of the share of that population that entered the country without the normal screening for foreign visitors or immigrants. That will remain the case unless and until the electronic US-VISIT entry-exit data control system required by legislation enacted in the wake of the 9/11 attacks is implemented.

There is good reason to believe, however, that estimates that place the overstayer share at about half — or even as low as two-fifths — of the total illegal population are misleading.

There is one study that provides some survey data that shed light on this issue. In 1992, the research firm Westat under contract for the U.S. Department of Justice conducted surveys among illegal aliens who received amnesty as a result of the 1986 Immigration Reform and Control Act.5 The survey asked into which of the two categories the amnestied alien fell. The result was that three-fourths of the amnestied population reported having entered illegally. The Westat survey, however, was conducted only among the 65 percent of amnesty applicants who applied on the basis of having been in the country since 1982. The other 35 percent of applicants applied on the basis of working in agriculture. We assume that the latter category of illegal aliens was comprised almost entirely of persons who entered illegally (There may have been a small number of illegal aliens from non-Latin American countries who fraudulently applied for amnesty as agricultural workers because they had not arrived prior to 1982).

If the 3:1 ratio of EWIs to overstayers found by the Westat survey were adjusted to include the agricultural worker amnesty beneficiaries the share of EWIs would rise to 84 percent vs. 16 percent for the visa overstayers.

The defenders of illegal aliens who claim that visa overstayers account for nearly half of the illegal alien population, or a greater share, should be prepared to explain why they believe that conditions since 1986 have changed dramatically. They should also provide evidence to support their contention. That would be a difficult task. Among the amnesty beneficiaries in the Westat study, 54 percent were from Mexico and Central America. If the agricultural workers were included in the calculation on the basis of the reasonable assumption that most of them also were from those same countries, the share from those countries would rise to 89 percent. The most recent estimate of the nationalities of the illegal alien population by the Pew Hispanic Center (2011) put the share of illegal aliens from those same countries at 81 percent – 58 percent from Mexico and 23 percent from other Latin American countries. 6 Given the assumption that most of the EWI illegal alien population come from Mexico and neighboring countries, it would seem not much has changed.

March 2011


  1. See http://en.wikipedia.org/wiki/Illegal_immigration_to_the_United_States.
  2. "Modes of Entry for the Unauthorized Migrant Population". May 22, 2006, Pew Hispanic Center.
  3. Warren, Robert, "Illegal Alien Resident Population," consulted March 7, 2011.
  4. "Illegal Immigration: INS Overstay Estimation Methods Need Improvement," GAO September 1995.
  5. "Report on the Legalized Alien Population, U.S. Department of Justice, INS, March 1992.
  6. Passel, Jeffrey and D'Vera Cohn, "Unauthorized Immigrant Population: National and State Trends, 2010," Pew Hispanic Center, February 1, 2011.