The PAC-10, which only sent two teams to the tourney, is now completely out, after Baylor downed Colorado on Saturday night. Additionally, the three Westernmost conferences - PAC-12, WCC and Mountain West - have all been dismissed, after Louisville polished off the last of the four Mountain West teams, New Mexico, in Saturday's last game.
Those three conferences sent a total of nine teams, and none have survived the first two rounds. The results speak for themselves. The best basketball is being played almost overwhelmingly East of the Rockies and the majority of that, East of the Mississippi River.
Here's the breakout of conference records through Saturday, March 17: