Data

Data Overview

The MMP Database is the result of an ongoing multidisciplinary study of Mexican and Central American Migration to the United States. It contains data gathered since 1982 in surveys administered every year in Mexico and more recently in Central America, and in the United States. The MMP Database (MMP174) is currently one of the most concise and vast data set of its kind in existence.

Our datasets are divided into two type of files: Core Files and Supplemental Files. Core files are the result of all the information gathered through the Ethnosurvey of households. Supplemental files, on the other hand, are built using external sources such as the Mexican census and DHS statistical yearbooks.

Core Files

The MMP174 Database contains an person level file with general demographic and migratory information for each member of a surveyed household (PERS). More detailed information on each migratory experience of all heads of household (and in more recent years spouses) is presented in a second file (MIG). In communities 120-174, whenever the household head was not a U.S. migrant, the MMP collected information about another person in the household with U.S. migration experience (MIGOTHER). Starting in 2005, the MMP gathers detailed information on migratory experience of all household heads and spouses who have migrated to Canada (CNMIG). More general characteristics of the household, its members, and other holdings is reserved for a fourth file (HOUSE). Lastly, detailed labor histories for each head of household and each spouse complete the set of data files (LIFE and SPOUSE, respectively).

PERS

A person-level file that provides general demographic information and brief migration measures for each member of a surveyed household, including children of the head of household not presently residing with their parents. Data include age, sex, relationship to head of household, marital status, current economic indicators, and characteristics of the first and last trips made to the US/other Mexican locations. Starting community 110, these data also include characteristics of the first and last trips made to Canada. Starting community 115, these file includes health variables for the household head and the spouse only. In addition, starting in community 162, we gather information about U.S. born children to Mexican parents who have returned to Mexico.

MIG

A person-level file containing details of all border crossings (up to 30) by each head of household, as well as measures of economic and social activity during the last U.S. visit. Data include the year, crossing location, documentation used, costs, method and whether deported for each border crossing. Starting in 2018, there is a set of questions regarding temporary workers.

MIGOTHER

A person-level file containing details of all border crossings (up to 10) by another person within a household whenever the household head is not a migrant. This file contains measures of economic and social activity during the last U.S. visit. Data include the year, crossing location, documentation used, costs, method and whether deported for each border crossing. Also, measures of economic and social resources during the most recent U.S. trip are included. Data are available starting community #120. Starting in 2018, there is a set of questions regarding temporary workers.

CNMIG

A person-level file containing details of first and last trips to Canada by the household head or any other migrat. We gather measures of economic and social activity during the most recent trip to Canada. Data are available starting community #110. In 2018, more detailed questions regarding temporary workers were added.

HOUSE

A household-level file containing information on household composition, economic and migratory activity of household members, land ownership and usage, home/real estate ownership and amenities, vehicle and livestock ownership and financing, and business ownership and operation. In 2017, a set of questions regarding violence perception were included.

LIFE

An event-history file detailing the labor and family histories of each head of household, for each year since birth until the year of the survey. These data are supplemented by various time-constant variables gleaned from the previous four data files.

SPOUSE

An event-history file detailing the labor histories of each spouse of a household head, for each year since birth until the year of the survey.

Supplemental Files

In addition to the six primary data files, supplementary data files have been created to provide researchers with additional information that may be useful in analyses of migration. For instance, for all the communities surveyed by the MMP, data at the community and municipio level have been collected and compiled in the file: COMMUN. Also, we have made available the annual prevalence ratios per community from 1940 up to the survey year under the file PRATIO.

Other two supplementary data files - NATLYEAR & NATLHIST - are available to you as well. These two dataset contain several variables that have been used by MMP researchers in the past to assess various factors contributing to migration between Mexico and the U.S.

Also, we are now offering a supplementary data file at the state level, which contains detailed environmental data: ENVIRONS. Some of the variables in this dataset are: type of weather, land use and degradation, and history of monthly rain (from 1941 to 2004).

Community Level

COMMUN

A community-level file that provides information regarding community and municipio characteristics from 1950 to the time of the survey. Included is information regarding population, labor force, industry, natural resources, agriculture, standard of living, community development, infrastructure, institutions, and migration prevalence. We also offer homicides rates from 1990 to 2019.

PRATIO

A community-level file that provides the annual migration prevalence ratio starting in 1940 up to the survey year. Prevalence ratio was first described by Douglas Massey et. al. in their article "Continuities in Transnational Migration: An Analysis of Nineteen Mexican Communities." American Journal of Sociology Vol. 99, No. 6 (May 1994), pp. 1492-1533.

State Level

ENVIRONS

A state-level file that provides information regarding weather type, rainfall by month and year, garbage amounts, land use and land degradation.

National Level

NATLYEAR

A longitudinal supplemental file containing several national-level indicators of macroeconomic conditions in the United States and Mexico from 1965 to 2017: border crossing measures, INS budget and activities, intra- and inter-country financial indicators, trade levels, and workforce statistics.

NATLHIST

A longitudinal supplemental file containing selected indicators of Mexico-U.S. migration, border enforcement, population, and trade for each year from 1900 through 2017.

MSA Level - no longer updated

MSACROSS

A cross-sectional supplemental file providing the cost of living index (1983) for each U.S. urban geographic code contained in the MMP files (as of June 1997), allowing researchers to adjust for differences in price levels across metropolitan areas at a particular point in time.

MSAYEAR

A longitudinal supplemental file containing information on the consumer price index (base 1982-84), unemployment rate, number of Mexicans who became legal residents as a percent of the total Mexican foreign-born population and total population size for all U.S. urban areas used in the MMP (as of June 1997), over selected years.

Accessing the Data

After submitting this form, you will be redirected to the Brown Digital Repository to download the data.

The data is currently available for SPSS and STATA file formats.

How to Cite the MMP and its Data

THE MMP

You may introduce the MMP using a quote such as the following: "The Mesoamerican Migration Project (MMP) is a collaborative research project based at the Brown University and El Colegio de Mexico".

Please, cite the MMP website: mmp.research.brown.edu

Other references to the MMP or its survey methodology can be taken from our website at your discretion. For example, consider reporting that the survey questionnaire is available on this website. When citing our website, refer only to the address specified above and not to specific menus within it, as the website design may change over time. There is no need to use quotes when copying text from the MMP website.

THE MMP DATA BASE: MMP174

We ask you to cite the current MMP database as "MMP174." For your reference, the number 174 stands for the number of communities included in the database. It does not represent the number of communities included in a user's own work. Thus, in case you decide to discard data from one or more entire communities, we still ask you not to change this reference and cite your original data source as "MMP174."

IF YOU ARE USING A PREVIOUS VERSION OF THE DATA BASE...

MMP170 was released on February 2019. If you are using the previous version of the MMP Data Base, which contained 161 communities, we ask you to refer to it as "MMP161."

IF YOU PUBLISH...

Please let us know if you publish any research that uses MMP data by sending a message to mmp_lamp@brown.edu

Updates and Changes to the Database

MMP177 will be available in spring 2025!