The issue of immigrant children pouring across the Texas border can, and in the end, must be understood as US foreign policy coming home to roost.  
Our historic good fortune and protection on east and west coasts by oceans has helped foster the delusion that foreign policy– boring and “out there”– and domestic policy are separate, which in fact they are not.  The terrorized children from Salvador, Honduras and Guatemala are a crack in the egg of that delusion.
A country that does not send us terrorized refugee children is Nicaragua. Of these four countries, only Nicaragua  does not receive large, constant infusions of US military aid.  Nicaragua alone has not succumbed to US proxy military aggression.  (Remember Reagan’s “freedom fighters”, the illegally funded Contras?)  With poverty second only to Haiti’s, Nicaragua has a popular leftist government that actually provides services and security to its citizens including health care. 
Children are safe there, since there are no para military marauding gangs with US weapons, unlike Honduras, Columbia and Salvador.  The militarized right wing governments in these countries are the beneficiaries of US military aid year after year.  By these means the US insures the militarization of these countries whose children flee in terror  (“…foreign policy coming home to roost”.)  The support for right wing militaries, para militaries and dictators in these countries create a climate of fear and deep insecurity and lawlessness.  
Regarding many of the letters to City,  a confusion and distortion arises from a lack of perspective about the relationship of foreign-domestic policy.  This can be seen in the complaints about “costs to taxpayers.”  The complaints are easy enough to understand and sympathize with, but they completely distort meaningful perspective since our foreign policy and militarized economy are non productive, hugely destructive, and cost trillions, not millions or billions.  The taxpayer cost for social programs cannot be understood at all without reference to the elephant in the living room of military costs and the gross hubris of our unsustainable overreach and domination abroad.  Our foreign policy of hegemony is not working, and one proof is in the pudding of fleeing, terrorized children.
Mike Connelly