By 2003, ...the roughly 20 million Mexican-origin workers in America create a larger gross product than Mexico itself.
...Five predominantly rural Mexican states—Guanajuato, Jalisco, Michoacán, San Luis Potosí, and Zacatecas—send a disproportionately large number of emigrants to the United States...Home to less than a third of Mexico’s population, they receive 44 percent of Mexico’s remittances.
[In contrast,] The relatively small remittance flow to Mexico’s border states attests to their economic strength. The spread of factories along the border to perform cheap manufacturing for U.S. companies allows many Mexicans to find work without crossing over.
As long as they assimilate, more immigrants are a win.