English language ability
The Mexican Migration Project (MMP) includes self-reported information on language ability for each household head on his last trip to the US. This variable provides information on the language ability in five categories: (1) doesn't speak nor understand English, (2) doesn't speak but understands some English, (3) doesn't speak but understands well, (4) speaks and understands some English, (5) speaks and understands English well. For our estimations, we combined categories (2) and (3) and categories (4) and (5) in order to have enough individuals in each language group.
The most recent information on the number of unemployed and the size of the civilian labor force at the county level was obtained for the years 1974 and 1976–1996 from the Bureau of Labor Statistics, Local Area Unemployment Statistics Division. For the early 1970s, no information by county is available, although information on unemployment for the censual years 1960 and 1970 is available. For the years 1971–1973, the assumption was made that unemployment rates in a county follow the same trends as that of the state. An estimate of the unemployment rate for 1975 was obtained by averaging the unemployment rates for 1974 and 1976. Source: MMP 52.
Data were obtained from Census publications, e.g., the CPS and County and City Yearbook, for the following years: 1970, 1974, 1976, 1977, 1980, 1984, 1986, 1987, 1990, and 1991. The population for the intercensual years was estimated by assuming an exponential growth function. To estimate the population between 1992 and 1995, the constant growth rate that prevailed between 1980 and 1991 was applied. Source: MMP 52.
We collected data on three measures of migration costs. For Miles and Hours, we entered in the main town in the Mexican state in which the origin village is located and the main town in the US location into Mapquest (http://www.mapquest.com). For Actual Costs, the data come from the MMP 52. Since the actual cost data were very sketchy, we decided not to use it. Trials with the Hours and the Actual Costs data yielded similar results to those when we used Miles.
Mexican share of population
This variable has been obtained from the US Census Bureau for the censual years 1970, 1980, and 1990. A second-degree polynomial equation was estimated to these three data points to estimate the size of the Mexican foreign-population in each area during the intercensual years. To estimate the Mexican foreign-born population in the years 1991–1995, it has been assumed that the annual growth rate during this period is the same as the annualized constant growth rate in each area between 1980 and 1990. The size of the Mexican foreign-born population is then divided by the Total Population in a US location. Source: We thank Julie A. Phillips for making this variable available to us.
Number of current migrants
To calculate these variables, we make use of an event-history file provided by the MMP. This event-history file contains detailed labor and family histories of each household head, for each year from the birth of the household head until the year of the survey. Donato et al. (1992) provide a description of the event-history file. Using this event-history file, we calculated for each year t the number of current migrants from the Mexican community k in the US community j.
Imperial Valley, CA; Lower San Joaquin, CA; Middle San Joaquin, CA; Upper San Joaquin, CA; Salinas–Monterey–Santa Cruz, CA; Sacramento Valley, CA; Ventura–Oxnard–Simi, CA; Santa Barbara, CA; Napa–Sonoma, CA; Los Angeles County, CA; Orange County, CA; San Francisco Urban Area, CA; San Jose Urban Area, CA; Riverside–San Bernardino, CA; San Diego County, CA; Rio Vista, CA; Abilene, TX; Austin, TX; Beaumont–Port Arthur, TX; Brownsville, TX; Bryan–College, TX; Corpus Christi, TX; Dallas–Ft. Worth, TX; El Paso, TX; Galveston, TX; Houston, TX; Laredo, TX; McAllen, TX; Odessa–Midland, TX; San Antonio, TX; Victoria, TX; Chicago, IL; Las Cruces, NM; Tucson, AZ; Phoenix, AZ; Denver–Boulder, CO; Reno, NV; Las Vegas, NV; Omaha, NE; New York City, NY; Washington D.C., WA; Miami, FL; Atlanta, GA.