Sudden drastic change in migration & population trends?

In another thread that this question wouldn't really belong in, I spotted this statement:

Quote:

Originally Posted by TraneWreck (Post 11820269) net crossing of the Mexican border has been close to zero for a few years now.

What organization published the data here? Why does it seem to have escaped everyone's attention so far? And, given that it was previously said that American population increase is mostly caused by immigration rather than internal reproduction above replacement rate, what effect would this have on the growth of the overall population if the current trend were to continue?