I, too, was referring to that post (#3). It was “immediately above” mine (#5) when I first started writing it. I did not notice yours (#4) before I posted.
Anyway, “tier 1” in USNews parlance refers to many more than just 5 colleges … and I’m not aware of any other major college ranking that uses “tier” distinctions at all. The Barron’s Profiles do group schools into 4 categories by selectivity. Category 1 includes more than 80 schools.