For years, employers in the United States have counted on a steady flow of laborers from Mexico willing to accept low-skilled, low paying jobs. These workers, many of whom leave economically depressed villages in the Mexican interior, are often willing to work for wages well below both the U.S. minimum wage and the poverty line. A dramatic demographic shift currently taking place in Mexico, however, may alter the trend: the stream of workers migrating from Mexico to the United States might one day greatly diminish if not cease.

As a result of a decades-long family planning campaign, population growth, which had reached a peak of 3.5% in 1965, declined to just 1% by 2005. On average, Mexican women today are giving birth to fewer than half as many children as did their mothers. The campaign, organized around the slogan that "the small family lives better," saw the Mexican government establish family-planning clinics and offer free contraception. For nearly three decades, the government's message concerning population has not wavered. In fact, the Mexican Senate recently voted to expand public school sex education programs to kindergarten.

For two primary reasons, Mexico's new demographics could greatly impact the number of Mexicans seeking work in the U.S. First, smaller families directly limit the pool of potential migrants. Second, the slowing of Mexico's population growth has fostered hope that Mexico will develop a healthy middle class. Though the former of these factors is all but assured, the growth of a healthy middle class is far from a foregone conclusion. The critical challenge for Mexico is what it does with the next 20 years. Developing a stable middle class will require investments in education, job training, and infrastructure, as well as a social-security system to protect its aging population. Businesses will need to create more semi-skilled and skilled jobs in construction, manufacturing, and technology, as well as the associated "white collar" jobs that too many Mexican manufacturers currently locate outside of the country's borders. It remains to be seen whether government and industry will answer these challenges as vigorously as the family-planning campaign answered the problem of population growth.