How many undocumented immigrants there really are, and why the number matters – Mohammad Fazel-Zarandi

MIT Sloan Senior Lecturer Mohammad M. Fazel-Zarandi

From Daily News

How many undocumented (illegal) immigrants are there in the United States? Previous estimates put the number at around 11-12 million.

These estimates are too low. That’s because they are based on surveys that ask individuals where they were born. This approach doesn’t work well for undocumented immigrants. They are hard to track down. They don’t want to be found. And if they are found and asked this question — where are you from? — they have every reason to refuse to answer or answer untruthfully.

In a new study, we estimate the number of undocumented immigrants using a different approach that doesn’t rely on surveys. And we get a very different answer. We estimate that there are at least 16.7 million and most likely more than 20 million.

Our approach is to estimate the inflows of undocumented immigrants (how many are entering the United States each year) and the outflows (how many are leaving). Inflows include border crossings and visa overstays. Outflows include deportations, conversions to legal status, deaths and voluntary emigration.

Adding up the inflows each year and subtracting the outflows gives an estimate of how many undocumented immigrants remain in the country at the end of the year compared to how many there were at the beginning of the year. We use operational data, especially from the Department of Homeland Security, as well as data and analysis of the movements of undocumented immigrants across borders. We estimate inflows and outflows every year from 1990 to 2016.

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