The vast majority of undocumented migrants from Mexico were gainfully employed before they left for the United States. Thus, failure to find work at home does not seem to be the primary reason that the estimated 6.3 million undocumented migrants from Mexico have come to the U.S. Policies aimed at reducing migration pressures by improving economic conditions in Mexico may also need to address factors such as wages, job quality, long-term prospects and perceptions of opportunity.