Between 1995 and 2000, with the U.S. economy booming, nearly 3 million Mexicans migrated to the United States. Taking out the 670,000 that moved back to Mexico, the result was an increase of over 2 million Mexican residents. In 1990, half of those migrants were under the age of 30.
That is probably still a conception that Americans hold about Mexican migrants: The numbers keep increasing as young men cross the border. But it's not quite right.