The Republicans have not won a Presidential election since 1928 without a Nixon or a Bush on the ticket.
The predictive value of this interesting trivia is about the same as Hillary Clinton's claim today that no Democrat has won a Presidential election without winning the Ohio primary.
It's just as meaningless.
There have only been six Democratic Presidents since the first Ohio primary in 1906. Despite Clinton's claim, only four of them at most ever won a Ohio primary. Neither John Kennedy nor Lyndon Johnson ever won the Ohio primary -- a favorite son candidate won the Ohio primary in 1960 and 1964. Furthermore, the nomination battle was already over when Bill Clinton won in 1992 so he also never won a competitive Democratic primary in Ohio.
In 1988, ‘92 and ‘96, the Ohio primary took place late in the process. Voters in each party primary voted for the eventual nominee of the party.
History of Ohio Primary/
So, Hillary Clinton is apparently basing her entire case on presumably competitive victories won by Woodrow Wilson, Franklin Roosevelt and Jimmy Carter in both the Ohio primary and the general election.
On second thought, maybe there is more predictive value in the claim that the GOP can't win a Presidential election without a Nixon or a Bush on the ticket.
The spuriousness of Clinton's claim about the special meaning of her Ohio victory is explored in more detail by Al Giordano at
The Field.