* Mayorkas announces 212,672 migrant encounters in July, says border is 'one of the toughest challenges we face' Fox News
* US encounters 'unprecedented' number of migrants at southern border, Homeland Security chief says CNN
* Watch live: Secretary of Homeland Security holds news conference in South Texas KPRC Click2Houston
* Mayorkas defends U.S. border strategy as migrant apprehensions reach 21-year high CBS News
* 'Unprecedented number': Migrant encounters at southern border topped 200,000 in July USA TODAY
* View Full Coverage on Google News
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