I have spent a lot of time in Mexico and Central America, having been a naturalist with Baja Expeditions and an international election observer in El Salvador the year that Mauricio Funes was elected. It was during that last commitment that I learned about the effects of immigration on the country of origin. The party of Mauricio Funes, the leftist party FMLN, presented workshops for the election observers. I attended one on immigration.
At the time, El Salvador had the largest percentage of its citizenry in the USA of any country. It was pointed out to us that immigration weakened El Salvador in several ways. First, it deprived El Salvador of its most energetic citizens (in the environment of a very corrupt ARENA government). Also, it decimated communities when a family member in the USA would send money and create artificial wealth for one family. Often that family would move into a gated community and cease its relationships with previous neighbors.
Third, it created the gangs causing so much chaos in Central America as MS 13 and others began among immigrants in Los Angeles and moved back to El Salvador. Lastly, the immigrants have mostly been of the poor and those that would have voted for change but could not in the USA. I share this just so that U.S. citizens know that allowing immigrants from Central America is only weakening the countries down there and the chances for reform.