illegal immigrants aliens arizone
There has remained considerable debate over the number of illegal immigrants in the country - a figure that obviously has great import in our ongoing debate over immigration policy. Now, Yale and the Massachusetts Institute of Technology have completed a study that that doubles the prior estimate of 11 million. That figure was used to argue for the passage of amnesty legislation. However, the study finds that the actual number is roughly 22 million.

In a video statement,Jonathan Feinstein, an economics professor at Yale states
This paper is not oriented towards politics or policy. I want to be very clear. This paper is about coming up with a better estimate of an important number, and we are really trying in this paper to keep away from making any statements about how that could or should be used. It is just a paper to help the debate be organized around some better information, which in my opinion is a good thing to do. I think the debate should always be centered around the best information we can develop.
Edward Kaplan, operations research professor at Yale said that they did the study expected a much smaller figure but the findings were clear. The study states:
The figure [below] also shows our conservative estimate of 16.7 million in Red, and the most widely accepted estimate heretofore of 11.3 million in Blue on the far left. We note that this last estimate is for 2015, but should be comparable since both the estimates based on the survey approach and our modeling approach indicate that the number of undocumented immigrants has remained relatively constant in recent years. Finally, the mean estimate of 22.1 million is shown in black in the center of the distribution.
alien chart
Notably, these numbers only include the years leading up to 2016 and thus do not include any added numbers from 2017 and 2018.

This estimate places the undocumented population at roughly 17 percent of the population.