Behind the Pew Study on Illegal Immigration, Part IV: The Mystery of the Missing 900,000 Illegal Immigrants
By Stanley Renshon, September 8, 2010

At the heart of the Pew report is the finding that the overall estimated numbers of illegal immigrants in the United States have declined from a peak of 12 million to 11.1 million, a net decline of 900,000 illegal immigrants. At least, this is what the report's title suggests that Pew believes is its most noteworthy finding. The decline is also the point that almost all accounts of the Pew report emphasize.

In this entry, I would like to "stipulate" the general accuracy for the report's numbers (which are, after all, close to CIS's own estimates from July of last year), even though obvious questions could be asked regarding their accuracy for the purpose of further inquiring into a very basic question: Where did those 900,000 illegal immigrants actually go?

What the report says about this has been largely overlooked. Missed in all the excitement about the decline in numbers was the wording of the report: "the annual inflow of unauthorized immigrants to the United States was nearly two-thirds smaller in the March 2007 to March 2009 period than it had been from March 2000 to March 2005" (p. i, emphasis added). To repeat, that is a decline in the number of people arriving. It does not represent a surge or even in the uptick of illegal immigrants heading home.

Here is how the Pew study phrases it: "during the first half of the decade, an average of about 850,000 new unauthorized immigrants entered each year, increasing the unauthorized population from 8.4 million in 2000 to 11.1 million in 2005. Since then, the annual inflow has dropped to about 550,000 per year from March 2005 to March 2007, and declined further to an average of 300,000 per year for March 2007 to March 2009. As a result, the unauthorized population in 2009 returned to the level it had been in 2005â€