One is that senators don’t have what it takes to win presidential elections. Obviously, if McCain clinches tonight, there will have to be one more counterexample of a senator reaching the White House in modern times (the other two are Warren Harding and Jack Kennedy). Of course, if it’s Hillary, the accomplishment will be properly asterisked that she would be returning to the White House, not quite the same thing.

The second historical trend that might get a challenge is the rule of the Sunbelt candidates. Since 1964, all winning presidential candidates have hailed from the South or California (yes, George H.W. Bush was a bit of a stretch, but technically the rule applies). Setting aside Huckabee (please), the only Sunbelt candidate in play is McCain.