The SIns That Cry To Heaven

I was working up some notes for a CCD class on sin, and as usual, went through a wormhole, ended up reading far afield of what I needed or what might be pertinent or appropriate for 5th graders.

Somehow, one of the tangents was the "sins that cry to heaven," and I ended up posting a question on the blog of a fellow who feels the US of A is guilty of ALL such sins, and had better reconsider her ways.
My post has not appeared, perhaps disappeared into the ether? or perhaps, deemed "offensive or off-topic"?

In any case, the question stands -- why, in rightly reminding us that the oppressing the poor, the widow, the orphan will ignite the Almighty's wrath, is oppression of the alien/stranger/foreigner left out?

Isn't that part of that sin that "cries to heaven" for redress?

Yeah, bringing it up opens a can o' political and partisan worms, but that can't be our concern as Catholics.