Numbers, Facts and Trends Shaping Your World

Unauthorized Immigrant Population: National and State Trends, 2010

by Jeffrey S. Passel, Senior Demographer, Pew Hispanic Center and D’Vera Cohn, Senior Writer, Pew Research Center


As of March 2010, 11.2 million unauthorized immigrants were living in the United States, virtually unchanged from a year earlier, according to new estimates from the Pew Hispanic Center, a project of the Pew Research Center. This stability in 2010 follows a two-year decline from the peak of 12 million in 2007 to 11.1 million in 2009 that was the first significant reversal in a two-decade pattern of growth.

The number of unauthorized immigrants in the nation’s workforce, 8 million in March 2010, also did not differ from the Pew Hispanic Center estimate for 2009. As with the population total, the number of unauthorized immigrants in the labor force had decreased in 2009, from its peak of 8.4 million in 2007.

The number of children born to at least one unauthorized-immigrant parent in 2009 was 350,000, essentially the same as it was a year earlier. An analysis of the year of entry of unauthorized-immigrant parents indicates that 61% arrived before 2004, 30% arrived from 2004 to 2007, and 9% arrived from 2008 to 2010.

According to the Pew Hispanic Center, unauthorized immigrants made up 3.7% of the nation’s population and 5.2% of its labor force in March 2010. Births to unauthorized immigrant parents accounted for 8% of newborns from March 2009 to March 2010, according to the center’s estimates, which are based mainly on data from the government’s Current Population Survey.

The decline in the population of unauthorized immigrants from its peak in 2007 appears due mainly to a decrease in the number from Mexico, which went down to 6.5 million in 2010 from 7 million in 2007. Mexicans remain the largest group of unauthorized immigrants, accounting for 58% of the total.

The decline in the population of unauthorized immigrants since 2007 has been especially marked in some states that recently had attracted large numbers of unauthorized immigrants. The number has decreased in Colorado, Florida, New York and Virginia. The combined unauthorized immigrant population of three contiguous Mountain West states — Arizona, Nevada and Utah — also declined.

The number of unauthorized immigrants may have declined in other states as well, but this cannot be stated conclusively because the measured change was within the margin of error for these estimates.

In contrast with the national trend, the number of unauthorized immigrants has grown in some West South Central states. From 2007 to 2010, there was a statistically significant increase in the combined unauthorized immigrant population of Louisiana, Oklahoma and Texas. The change was not statistically significant for these states individually, but it was for the combined three states. Texas has the second largest number of unauthorized immigrants, trailing only California.

Despite the recent decline and leveling off, the number of unauthorized immigrants living in the United States has tripled since 1990, when it was 3.5 million. The size of this population grew by a third since 2000, when was 8.4 million.

The estimates are produced using a multistage method that subtracts the legal foreign-born population from the total adjusted foreign-born population, with the residual then used as the source of information about unauthorized immigrants. The source of these data is the U.S. Census Bureau’s March Current Population Surveys.

Because these estimates are derived from sample surveys, they are subject to uncertainty from sampling error, as well as other types of error. Each annual estimate of the unauthorized population is actually the middle point of a range of possible values that could be the true number. Additionally, the change from one year to the next has its own margin of error.

Because of the margin of error in these estimates, two numbers may look different but cannot be said definitively to be different. For example, there is no statistically significant difference between the estimate of the unauthorized population for 2009 (11.1 million) and the estimate for 2010 (11.2 million). Similarly, some state estimates for single years are based on small samples; especially in less populous states, two single years should not be compared.

These ranges represent 90% confidence intervals, meaning that there is a 90% probability that the range contains the true value.

Although the estimates presented here indicate trends in the size and composition of the unauthorized-immigrant population, they are not designed to answer the question of why these changes occurred. There are many possible factors. The deep recession that began in the U.S. economy in late 2007 officially ended in 2009, but recovery has been slow to take hold and unemployment remains high. Immigration flows have tended to decrease in previous periods of economic distress.

The period covered by this analysis also has been accompanied by changes in the level of immigration enforcement and in enforcement strategies, not only by the federal government but also at state and local levels. Immigration also is subject to pressure by demographic and economic conditions in sending countries. This analysis does not attempt to quantify the relative impact of these forces on levels of unauthorized immigration.

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