The scientific journal PLoS ONE recently published a Yale-MIT study that claims that the number of illegal immigrants presently living in the U.S. is at least 50 percent greater than previous estimates — at about 12 million — and may even be twice as high.
“Estimating the size of the unauthorized population is a difficult task,” Texas Census Research Data Center director Mark Fossett said. “Many key sources of data are either unavailable or have significant quality problems. Professional demographers understand these issues and how to deal with them.”
Current consensus estimates by demography researchers such as the Center for Migration Studies and the Pew Research Center, immigration restrictionists such the Center for Immigration Studies and numbers from the Department of Homeland Security all independently put the illegal immigrant population between 10.8 million and 12.1 million.
“The PLoS ONE paper’s authors term its methods conservative, but this is a self-description by non-demographers,” Fossett said. “The methods crucially rely on ‘what if’ simulations incorporating assumptions that are speculative, not conservative.”
Three specific criticisms are leveled against the paper in an accompanying response article in the same PLoS ONE issue. Firstly, the novel mathematical model used in the paper is highly sensitive to assumptions about the number of people in the 1990s who entered the country illegally and those who remained. The commentary authors also argue that if there really was a significant number of extra unauthorized immigrants living in the United States, they would show up in other demographic and statistical surveys such as the U.S. Census and American Community Survey. Thirdly, they would also be detectable in employment statistics.
According to research by the libertarian think tank Cato Institute, illegal immigrants commit crime less often than U.S. natives. For example, based on current mainstream population estimates, the homicide conviction rate is 3.2 per 100,000 for natives in Texas, 0.9 per 100,000 for legal immigrants and 1.8 per 100,000 for illegal immigrants. About 13 percent of all unauthorized immigrants in the U.S. live in Texas, according to the Pew Research Center.
Assuming the same total number of crimes are committed in a year, an increase in the size of a group’s population leads to a reduction in its relative crime rate. Therefore, if the study’s estimates are distributed proportionally across states, this suggests that the relatively low illegal immigrant homicide conviction rate in Texas is actually much lower. Similarly, the existing crime rate gap between illegal immigrants and natives would be even larger — as acknowledged by the study’s authors.
Assistant sociology professor Ernesto Amaral said these results are consistent with the general findings of the academic literature — for the U.S., immigration reduces the crime rate.
“Overall, results indicate lower rates of crime among immigrants, compared to the native population,” Amaral said.According to a literature review by the National Academy of Sciences, immigration — both legal and illegal — has a small positive impact on long-term relative wages for native workers with a high school education and above, and a mixed effect for high school dropouts, who comprise the poorest 10 percent of the U.S. population. A larger illegal immigration population means these wage effects are likely significantly smaller. That is, immigration probably has almost no effect on long-term native wages — neither positive nor negative.
“They also highlight negative impacts of immigration on labor market outcomes, e.g., earnings, of native workers in the short-term, because there is a higher availability of workers, higher labor supply, competing for specific jobs,” Amaral said. “These negative effects tend to disappear over time, because of the creation of new jobs.”
The share of immigrants that the U.S. can sustain and integrate is the subject of frequent political discussion. The Census Bureau reports that the total foreign-born resident population was 13.7 percent of the U.S. population in 2017. The record is 14.8 percent set in 1890. On the basis of the study, the U.S. may currently have the highest share of immigrants in its history.
“In terms of integration, studies already indicate that by the second generation, immigrants already have socioeconomic status closer to the native population because children of immigrants learn the English language, are educated in the U.S. and gain skills to compete in the labor market,” Amaral said.
According to sociology professor Arthur Sakamoto, people should consider the full picture of the interconnectedness of the immigration issue when evaluating similar research on the topic.
“We have a lot of ideals, but we shouldn’t compartmentalize them,” Sakamoto said. “All of these [issues] have interlinkages. Immigration is part of the economic system, and so to be too ideological about any one part of the system, you don’t see how it affects the other parts of the system.”