Potential executive action by the White House, along with the recent surge in unaccompanied children attempting to cross the U.S.-Mexico border, has once again brought the political spotlight to America’s immigration system.

While much of the controversy over immigration reform is focused on how to deal with the estimated 11.1 million undocumented U.S. residents, there is also disagreement on how to reform the country’s legal immigration channels. For more than a decade, polling firms such as Gallup have found much more public support for decreasing immigration flows than for increasing them. Further, U.S. deportations reached a record high in 2013, even as the growth of the unauthorized population has stalled since 2009, according to the Pew Research Center.

But how do legal and illegal immigrants — also referred to as “unauthorized” or “undocumented” — to the United States differ? Are some groups more likely to choose one path or the other when immigrating? Once here, how does their method of immigration shape their choices and experience? A 2014 study in the Journal of Population Economics, “Empirical Characteristics of Legal and Illegal Immigrants in the USA,” explores these and other questions using data from the Census Bureau’s American Community Survey and the New Immigrant Survey, administered by Princeton University, primarily relating to the period from 2005 to 2007.

The authors, Vincenzo Caponi of Ryerson University and Miana Plesca of the University of Guelph, use a new statistical approach that allows them to better understand the characteristics and lives of those who live and work in the United States illegally — their typical demographic traits, how do they differ from the legal immigrants, and how their legal status impacts their human capital and returns to that capital. The study represents the first time researchers have made an attempt to quantify the characteristics of illegal immigrants from a random sample that is representative of that population.

The study’s findings include:

• Compared to legal immigrants, those who are undocumented are more likely to be less educated, male and lower paid. Being married with a spouse present in the United States increased the probability of having legal status. However, if the spouse is absent it increases the chance of being illegal.
• Older immigrants and those who are more educated are more likely to be legal. However, for immigrants coming from Mexico — the largest source of illegal immigration to the United States — the reverse is true in terms of education: The more educated they are, the more likely they are to be undocumented in the United States.
• African-born immigrants are more likely to be legally in the United States than Europeans, while Asians and Latin Americans are more likely to be undocumented.
• The scholars’ model also makes predictions for destination states: California, Texas and Arizona have more illegal immigrants than legal, Florida has around the same level of each and New York has more legal immigrants.
• Illegal immigrants suffer a large wage penalty at all education levels, although the penalty tends to decrease with education. For example, having some high school education but not a diploma seems to hurt legal immigrants, for whom the return is negative. However, illegal male immigrants get a positive return of about 5% from having more than elementary education.
• The construction trades attract the most illegal immigrants and “most of the immigrants in agriculture are also illegal.” By contrast, in sectors such as health care and retail trade, there seems to be a prevalence of legal immigrants. The unemployed are also more likely to be legal rather than illegal immigrants, perhaps explained by the fact that legal immigrants may have easier access to unemployment benefits.
• The fertility rate among illegal immigrant women is significantly higher than for those who are legal. In particular, among legal immigrants there is the typical relationship between increased education and reduced fertility. By contrast, the “total fertility rate among illegal immigrant women is significantly higher than that among legal ones, and that is particularly true for middle and higher educated women.” The researchers state that they do not have “an immediate or straightforward explanation for the differences.”

Due to the wide range of visitors to the United States who fit neither the legal nor illegal immigrant categories — for example, international students and high-skilled workers on temporary visas — caution must be applied to the data used in this study. However, the main results of the analysis still hold, the scholars state, after including and excluding categories of respondents who may be inaccurately represented. They conclude: “Our methodology should be of interest to all researchers who need to make some inferences based on legal or illegal immigrant status.”

Keywords: Hispanic, Latino, Mexico