Demography has uninterruptedly changed the course of human history. From the diaspora that led the formation of Ancient Greece to the aging populations of Japan and Europe. However, it is possible to assert that the speed of the demographic changes that North America has been going through is unprecedented.

The biggest change in this respect has been migration from the southern countries of Latin America to northern ones, particularly the United States. Not surprisingly, a large proportion of them come from Mexico since it accounts for over 30% of the Spanish speaking population in the Americas and shares a 3,145 km (1,954 mi) border with the United States, in many respects the most dynamic border in the world.

In fact, about one in ten Mexican citizens, 12m in total, live in the United States and despite ugly and divisive yet apparently fashionable political rhetoric half of them are legal and documented migrants. This makes for the biggest immigrant community in the world.

Has this migration come to a reach a new equilibrium? Between 1995 and 2000 some 3m Mexicans moved to the United States, vastly outnumbering the 700,000 or so who returned to Mexico. Yet in 2005-10 the number of newcomers fell to 1.4m, whereas that of returners increased to a matching 1.4m. Some estimates report that current net migration between these two countries has reversed. Much of this is likely to be the result of scarcer job prospects in the US, but not all.

Still, every year around 900,000 United States born citizens with Latin American heritage reach voting age. The effects of past migration are inevitable. The map that follows should help you visualize the size of the phenomenon.

It is not uncommon that people find a connection between the previews map and that of the mid 19th century before the territorial disputes between the United States and Mexico that were settled between 1845 and 1848 to favor the rising US power. The map to the right plots the Mexican territory as claimed by Mexico.

by Diego de la Fuente