I had long had this impression, and now the Olympics issue of Sports Illustrated confirms it: Californians are hugely over-represented on the Summer Olympics team.
"Based on hometowns, California produced more members of Team USA (175) than any other state."Indeed, the next seven states only produced 176 athletes.
Similarly,
"The colleges with the most team members (current students or alums) are Stanford (31), UCLA (19), USC (19), Texas (17), Cal (14), and North Carolina (13)."