The Pew Hispanic Center’s Survey of Mexican Migrants provides detailed information on the demographic characteristics, living arrangements, work experiences and attitudes toward immigration of 4,836 Mexican adults who completed a 12-page questionnaire as they were applying for a matrícula consular, an identity document issued by Mexican diplomatic missions. Fieldwork was conducted in Los Angeles, New York, Chicago, Atlanta, Dallas, Raleigh, NC, and Fresno, CA, from July 12, 2004, to Jan. 28, 2005.

The sampling strategy for the survey was designed to generate the maximum number of observations of Mexicans living in the United States and seeking documentation of their identity at a Mexican consulate. Respondents were not asked directly to specify their immigration status. However, slightly more than half of the respondents (N=2,566) said that they did not have any form of photo ID issued by any government agency in the United States. The share of respondents saying they had no U.S.- issued identity documents was much higher among the more recently arrived—80 percent among those in the country for two years or less and 75 percent for those in the country for five years or less.

The Survey of Mexican Migrants was a purposive sample, in which any individual seeking an identity document on the days the survey was in progress could choose to participate. It was not a probability sample, in which researchers randomly select participants in a survey to avoid any self-selection bias. Moreover, the results have not been weighted to match the estimated parameters of a target population as is often the case with public opinion surveys. Instead the data are presented as raw counts. Conducting a survey of matrícula applicants on the premises of Mexican consulates while they waited for paperwork to be processed permitted the execution of a lengthy questionnaire among a large number of individuals in the target population. No other survey on this scale has been attempted with Mexican migrants living in the United States.

The survey allows an extraordinary view of a population that by its very nature is exceptionally difficult to measure and study: Mexicans who live in the country without proper documentation and in particular those who have been in the country for only a few years. The survey data and other evidence suggest that a substantial share of the respondents, especially among those that are young and recently arrived, are not in the United States with legal immigrant status.

The matrícula consular is a laminated identity card that bears an individual’s photograph, name and home address in the United States and that attests that he or she is a citizen of Mexico. The card is issued by Mexican officials without inquiring as to the individual’s immigration status in the United States. As such, it cannot be used as proof of permission to reside or work in the country, and U.S. immigration authorities will not accept it as proof that the holder has the right to enter the country. However, the matrícula is accepted as an identity document that establishes the holder’s local address by many law enforcement agencies and local governments. The U.S. Treasury Department ruled in 2003 that the matrícula can be used to open bank accounts. Two-thirds of the respondents in this survey—3,265 individuals—said one of the reasons they were applying for the matrícula was to use as an ID card in the United States.

For individuals returning to Mexico, the matrícula can be used in place of a Mexican passport to enter Mexico at those points of entry, primarily airports, where Mexican authorities conduct immigration checks. And, 43 percent of the respondents said one of their intended uses of the matrícula was for travel to Mexico. However, an individual who plans to return to the United States legally will need a valid Mexican passport and some kind of U.S.-issued visa to reenter the country except for short visits near the border.

The act of applying for a matrícula consular is not evidence that an individual is an unauthorized migrant. However, a permanent legal immigrant who has established a domicile in the United States and has been in the country for an extended period of time has access to other kinds of identity documents. Under normal circumstances, such an individual should be in possession of a U.S.-issued document attesting to his or her immigration status, and that document can be used to acquire a Social Security card, a driver’s license or other forms of photo ID issued by government agencies in the United States.

Most tourists and business travelers are allowed to remain in the United States legally for no more than a year, and 90 percent of the survey respondents said they had been in the United States for a year or more. Temporary workers and others who are allowed to reside in the country for longer than a year on non-immigrant visas make up a very small share of the migrant flow from Mexico.

Over the past decade 80 percent or more of the Mexican migrants who have come to live in the United States on a long-term basis have added to the stock of the unauthorized population, according to estimates based on data collected by Mexican and U.S. government agencies. As a result of the substantial illegal flow in recent years, those estimates indicate that about half of the 10 million Mexican nationals living in the United States reside in the country without authorization.

The Survey of Mexican Migrants was conducted on the premises of the Mexican consulates in Los Angeles, New York, Dallas, Chicago, Fresno, Raleigh and Atlanta, but respondents were advised that this was not an official survey and that it would have no bearing on their business at the consulate. Mexican authorities cooperated with the fieldwork by allowing it to take place at the consulates. However, the design, development and execution of the survey, the compilation and analysis of the resulting data and the writing and editing of this report were under the full and exclusive control of the Pew Hispanic Center. Consulate personnel did not take part in any of the fieldwork, and all of the costs of conducting the survey were borne by the Pew Hispanic Center. Fieldwork was conducted by International Communications Research of Media, PA, and Einat Temkin, of the University of Southern California Annenberg School for Communications, who served as fieldwork coordinator. Respondents could complete the questionnaire themselves, seek the assistance of an interviewer for any part of it or have the entire questionnaire read to them by an interviewer. All of the fieldwork was conducted in Spanish.

The sites for the survey fieldwork were chosen with several objectives in mind. One was to cover the major concentrations of the Mexican migrant population; hence the choices of California, Illinois and Texas. There was also a desire to produce a mix of locations with well-established immigrant populations, such as Los Angeles, and relatively new immigrant populations, such as Raleigh. And the survey sought a mix of major metropolitan areas, smaller cities and at least one site where a sizeable share of the Mexican population works in agriculture (Fresno). Thus there are some significant variations in demographic characteristics among the samples generated in the various cities.

No researcher has attempted to conduct a survey of a nationally representative sample of the undocumented population that was drawn with the level of statistical certainty that is routine for large-scale public opinion polls, and this survey does not purport to present that kind of sample. Within limits inherent to the nature of the target population, however, the Survey of Mexican Migrants offers an opportunity to examine this population at a level of detail and with a level of confidence not available heretofore.

Neither the U.S. Census Bureau nor any other U.S. government agency conducts a count of unauthorized migrants or defines their demographic characteristics based on specific enumeration. There is, however, a widely accepted methodology for estimating the size and certain characteristics of the undocumented population based on census data. The survey respondents resemble the undocumented population of Mexican origins in recent estimates in their age and gender and the amount of time they have been in the United States.


Data collection was conducted at Mexican consulates in Los Angeles, New York, Chicago, Atlanta, Dallas, Raleigh, and Fresno from July 12, 2004, to Jan. 28, 2005. In each location, data collection was conducted for five or 10 business days, depending on the estimated size of the target population in each city. In most cases, applicants for a matrícula consular are guided through a series of stations, where documents are examined, applications are submitted, photos are taken, etc. Depending on the number of applicants, the efficiency of the work flow and conditions at the consulate, the applicants could spend anywhere from 20 minutes to four hours at the consulate during their visit. In some locations, the matrícula applicants were concentrated in one room or area, while in other locations applicants for all types of documents were in one line or area. Therefore, recruiting only those who were applying for the matrícula consular was a primary concern. This was usually achieved by asking potential participants to identify themselves as matrícula applicants. Only respondents who replied affirmatively to the first question on the survey, asking if they were applying for a matrícula consular that day, were included in the survey data. Respondents were not asked for their names or any other identifying information at any point in the process.

Potential respondents were informed that they were eligible to participate in the survey using public announcements (with or without microphone, depending on the facilities) and individual recruitment. They were asked to fill out the survey while waiting in line to conduct their transaction or while waiting to pick up their newly obtained identity card. The participants received a verbal explanation regarding the survey, its content, the nature of the questions and the length of time needed to fill out the survey, as well as a detailed explanation of the anonymity and confidentiality of their responses. In addition, they were verbally informed that upon completion of the survey, they would receive a phone card which could be used to telephone Mexico as a token of gratitude for their time and patience. Potential participants were also given a detailed information sheet that explained more fully the purpose and implications of the survey. Both during the recruitment process and on the information sheet potential participants were advised that their dealings with the consulate would not be affected in any way by their decision whether to take the survey or not or by their responses.

Those who expressed an interest in participating in the survey and were of age had the choice of self administering the survey independently or having an interviewer read out the questions and fill in the questionnaire for them. Because the targeted sample is characterized by a high rate of illiteracy, special attention was paid to the potentially illiterate or semi-literate people in the sample by emphasizing that reading and writing was not a prerequisite to participation and that interviewers were available to provide assistance and to conduct as much of the survey as necessary.

Participants were then given a copy of the survey, a pencil and a clipboard. They were told to take as long as needed and to come back to any of the interviewers if they had any doubts or questions. Those participants who opted to have an interview conducted were usually interviewed in line or by the interviewers’ table. When completed, the survey was returned to an interviewer. It was then checked to assess whether the participant had completed the survey. While participants could skip questions if they so desired, there were some cases in which the participant had stopped marking responses entirely. In these cases, an effort was made to have the participant complete, as much as possible, the remainder of the survey. Interviewers offered to conduct the rest of the survey in an interview by reading questions and marking the answers. If the participant refused to complete the survey, either independently or through an interview, their survey was marked incomplete.

The survey was conducted under the auspices of the University of Southern California Annenberg School for Communication and was subject to the university’s regulations on human subject research. Respondents were advised of their rights under these regulations and were given phone numbers where they could call to register complaints or note any concerns about the conduct of the survey. Completed survey forms were marked as such and numbered per day. In addition, all completed surveys were checked in the field for any open-ended comments. Responses and all other handwritten text were translated into English for future coding and data entry. The translations were written underneath or in proximity to the original handwritten comment and placed in parentheses to distinguish the translation from the subject’s comments.

Each day’s completed survey forms were then sent to the offices of International Communications Research (ICR) in Media, PA, where data entry was conducted and a database established. The completed surveys are stored at ICR using procedures that accord with university regulations for maintaining the confidentiality and security of the data.

Sample Comparisons

Neither the U.S. Census Bureau nor any other U.S. government agency conducts a count of unauthorized migrants or defines their demographic characteristics based on specific enumeration. There is, however, a widely accepted methodology for estimating the size and certain characteristics, such as age and gender, of the undocumented population based on census and survey data. This methodology essentially subtracts the estimated legal-immigrant population from the total foreign-born population and treats the residual as a source of data on the unauthorized migrant population (Passel et al., 2004; Lowell and Suro, 2002; Bean et al., 2001).

Using this methodology, Jeffrey S. Passel, a veteran demographer and a senior research associate at the Pew Hispanic Center, has developed estimates based on the March supplement of Current Population Survey (CPS) in 2003, the U.S. Census Bureau’s annual effort to measure the foreign-born population and provide detailed information on its characteristics. Comparing the sample from the Survey of Mexican Migrants with these estimates demonstrates significant similarities with the estimated characteristics of the undocumented population.

Overall the survey sample has the same preponderance of males as the full Mexican-born population from the CPS. However, a greater share of the sample respondents are concentrated in the younger age ranges than in the Mexican-born population as a whole; and in this respect, the survey sample resembles the estimated characteristics of the undocumented population, with the share under 40 being identical. A greater share of the survey respondents are recently arrived in the country (five years or less) than in the full Mexican population, and again this resembles the undocumented population. In terms of education, the share of survey respondents that went as far as high schools is the same as that in the estimates of the undocumented population and the Mexican-born population as a whole. Differences emerge at the high and low ends of the educational profile.