who settled in the United States with the number who stayed in Mexico. Once the data are weighted, they are representative only of the population in the predetermined sampled communities, not of Mexico or of any well-defined geographic area in Mexico.27
The MMP contains detailed information on U.S. migration, including timing and location of illegal border crossings; number of failed attempts; smuggler usage and cost; past trips; U.S. destination, occupation, wages, and social ties; and duration of trip. It includes data on nonmigrant households as well, which is useful in modeling the migration decision. MMP data have been thoroughly documented and are widely used in the migration literature (see, e.g., Durand and Massey, 2004), but they are almost never used to measure migration flows.
THE MEXICAN MIGRATION FIELD RESEARCH PROGRAM
The Mexican Migration Field Research Program (MMFRP) was established in 2004 at the Center for Comparative Immigration Studies (CCIS) at the University of California, San Diego, which remains a cosponsor. It has been funded through multi-year grants from the Ford Foundation, the University of California Office of the President, and smaller extramural grants. By following migrants in rural Mexico and the United States over time, the MMFRP seeks to document and explain changes in their migration and settlement behavior.
The MMFRP follows three small, rural Mexican communities and their U.S. satellite communities over time.28 One community is interviewed per year and is then re-interviewed at two- or three-year intervals. Since 2004, the study has rotated between the three cities: San Miguel Tlacotepec, Oaxaca; Tlacuitapa, Jalisco; and Tunkas, Yucatan.29 The three small communities of fewer than 3,000 people were chosen to be “broadly representative of high-emigration communities in west-central and southern Mexico” (Cornelius et al., 2009:x). Similar to the MMP, the MMFRP administers household surveys to residents in the small towns at times when seasonal migrants are most likely to be present, typically in the months of January or February. The U.S. part of the survey is administered using a “snowball” technique, where participants in Mexico give contact information for their friends and family in the United States so that they may also answer
27 See The Mexican Migration Project Weights on the MMP website: http://mmp.opr.princeton.edu/databases/studydesign-en.aspx.
28 One community, Las Animas, Zacatecas, was interviewed just once in 2005.
29 Tlacuitapa was interviewed in 2005, 2007, and 2010; Tunkas in 2006, 2009, and 2012; and Tlacotepec in 2007-2008 and 2011.