Border enforcement efforts to keep Mexican migrants out of the United States have unintentionally led to them staying in the country for longer periods. As a result, family reunification occurs as male workers bring their wives and children, including today's Dreamers. The likelihood of Mexican migrants returning home after their first trip to the US has decreased from 50% in 1980 to zero in 2010. Research suggests that if the US had not increased border enforcement over the past 30 years, the undocumented Mexican population in the US would be one-third lower than it is now. The conclusion drawn is that attempting to solve the issue of illegal Mexican migrants has ironically worsened the problem.