The reputations of these prestigious schools were originally established with the intention of having one such school in each of the original northern U.S. states — Dartmouth in New Hampshire, Harvard in Massachusetts, Brown in Rhode Island, Yale in Connecticut, Columbia in New York, Princeton in New Jersey, and the University of Pennsylvania.
Cornell wasn’t among the original institutions that are now considered the “Ivy League.” It was established later as a land grant school in the 1860s.
The second-oldest college in what is now the US is William and Mary College in Virginia. It’s not an Ivy (and not in a northern state), but a book back in the 1980s about “the public Ivies” included William and Mary among them.