Interesting argument by Robert Dunn on “How the Mexican Immigration Problem will Solve Itself”:

There has been a stunning decline in the fertility rate in Mexico, which means that, in a few years there will not be many teenagers in Mexico looking for work in the United States or anywhere else. If this trend in the fertility rate continues, Mexico will resemble Japan and Italy – rapidly aging populations with too few young workers to support the economy.
According to the World Bank’s 2007 Annual Development Indicators, in 1990 Mexico had a fertility rate of 3.3 children per female, but by 2005, that number had fallen by 36 percent to 2.1, which is the Zero Population Growth rate. That is an enormous decline in the number of Mexican infants per female. The large number of women currently in their reproductive years means that there are still quite a few babies, but as this group ages, the number of infants will decline sharply. If this trend toward fewer children per female continues, there being no apparent reason for it to cease, the number of young people in the Mexican population will decline significantly just when the number of elderly is rising. As labor markets in Mexico tighten and wage rates rise, far fewer Mexican youngsters will be interested in coming to the United States. Since our baby boomers will be retiring at the same time, we could face a severe labor shortage.
There have been significant declines in fertility rates across Latin America, but Mexico’s has been unusually sharp. In El Salvador, another country from which immigrants come, a 3.7 rate in 1990 became 2.5 by 2005. Guatemala is now at 4.3, but that is far lower than it was in 1990. Jamaica, another source of illegal U. S. immigrants, has fallen from 2.9 to 2.4 over the same period. Chile and Costa Rica, at 2.0, are actually slightly below a replacement rate. Trinidad and Tobago, at 1.6, is well below ZPG. For all of Latin American and the Caribbean, a rate of 3.2 in 1990 fell to 2.4 in 2005, a decline of 25 percent. This means less pressure on the United States from illegal immigrants from the entire area, not just from Mexico. A powerful demographic transition is well underway, and soon many of these countries may be worried about there being too few babies rather than too many. We may miss this labor, and wonder how we will replace it.