Estimates of the Unauthorized Population

About the Data

A project by the Center for Migration Studies of New York (CMS) led to the development of these estimates on the size and characteristics of the unauthorized population in the United States at the national, state, and sub-state levels.  The purpose of this project is to make the information directly available to a wide cross-section of users.

To derive the estimates, a series of statistical procedures were developed based on microdata collected by the US Census Bureau’s American Community Survey (ACS). The ACS is an annual statistical survey covering approximately one percent of the total US population. The survey provides detailed social and economic data for all states, as well as all cities, counties, metropolitan areas, and population groups of 100,000 people or more.

The methodology involved three major steps:

  1. Applying a series of “logical edits” to identify and remove as many legal residents as possible from the ACS data for non-citizens who arrived after 1981;
  2. Deriving separate population controls, for 145 countries or areas, for unauthorized residents surveyed in the 2010 ACS; and
  3. Using those population controls to select records in the ACS micro-data (public use microdata sample (PUMS)) to be classified as unauthorized residents.  A final set of adjustments was made to account for undercount in the ACS.

The term “logical edit” refers to the process of determining probable legal status by examining survey data.  Respondents were assigned to the legal resident category if they worked in occupations that generally require legal status, were legal temporary migrants, were immediate relatives of US citizens, received public benefits, were from countries where most arrivals would be refugees, or were age 60 or older at entry.

A detailed description of the project and the methodology is available at: Robert Warren, 2014 “Democratizing Data about Unauthorized Residents in the United States: Estimates and Public-Use Data, 2010 to 2013.” Journal on Migration and Human Security. DOI:

Read more:

Using the Tools

This site offers two tools which essentially operate the same way and provide the same data, although for different geographic areas.

The State Data Tool provides data for selected states within the US.  To obtain the national estimates, do not click on any state.  To obtain state estimates, click on the specific state or states.  If you select multiple states, the tool will aggregate those states (sum them together), so that you can use the tool to regionalize.  For example, you can select all states that share a border with Canada or Mexico.  Remember to scroll down to view all results.

The PUMA Data Tool allows you to hone in on public use microdata sample areas (PUMA) areas – sub-state areas in the US that have a minimum population of 100,000.  PUMAs are a specialized geography created by the US Census Bureau in partnership with states, so that microdata samples can be used to create user-defined data sets.  Similar to the State Data Tool, users can use the PUMA tool to select multiple PUMAs in order to aggregate estimates.  Scroll down to view all results.

Note, however, that the geography of a PUMA will not necessarily “match” an existing city or county.  As you hover over a PUMA on the map, descriptive names of the PUMA will appear to describe the general boundaries for that PUMA.  In addition, you can type in descriptive names in the search bar in order to identify cities or PUMAs, and the map will zoom to that area.

Although these PUMA labels can help users identify areas, we also recommend that users learn more about this geography at the following links to the Integrated Public Use Microdata Series (IPUMS) at the Minnesota Population Center of the University of Minnesota:

Saving Your Data

To save your data, click on either the Excel or Word icons located below each map to download the file and save to your local computer.

Published by the Center for Migration Studies, all rights reserved.
Based on the augmented American Community Survey based IPUMS (Integrated Public Use Microdata Series)
Web tool developed and maintained by the IBRC at Indiana University.