Projecting Trends in Undocumented and Legal Immigrant Populations in the United States

We use administrative data on over 9 million Matr´ıcula (identification) cards issued by the Mexican government between 2008 and 2017 to Mexican-born individuals living the United States to improve estimates of the undocumented foreign-born population. These cards are held by those who do not have legal status in the United States and therefore do not have other forms of valid identification. The key contribution of our work is to use this data to produce estimates of the undocumented population from Mexico and from other countries, carefully laying out the relevant issues, assumptions, and sources of uncertainty. The ability to use the Matr´ıcula data to inform estimates of the undocumented population is particularly important because of the general lack of direct data on this group. Our preferred estimates indicate that there were on average 8.3-8.7 million undocumented Mexican individuals in the United States per year between 2008 and 2012 and 7.5-8.2 million between 2013 and 2017; both estimates are somewhat higher than the well-known estimates produced by the Pew Center. Our estimates of the undocumented immigrant population from other Latin American and Caribbean countries are more closely aligned with those from the Pew Center. Finally, we conclude that Matr´ıcula data is unlikely to be useful in estimating the undocumented population from outside of the Latin America and Caribbean region.