Wow, this is an interesting factoid.

Migration Tops Death in Mexico
By Associated Press
May 3, 2007, 7:51 PM EDT

Mexico has lost more people to migration to the United States than death since 2000, according to a government report released Thursday.

Mexico's demographics agency found that an average of 577,000 people migrated to the U.S. each year between 2000-2005, compared to 495,000 deaths a year in the same period. In 2006, 559,000 migrated and there were 501,000 deaths.
Migration Tops Death in Mexico - Newsday.com