87. "I think much more so historically than recently" In response to In response to 86
But its a tough data set because presidential campaigns are infrequent.
So, if I go back to the last time an incumbent president was defeated, it was 1992 and Al Gore helped Clinton carry Tennessee. Clinton very well might have won TN without Gore though.
So, to answer your question, I don't think there's any real recent evidence of that. But situationally I think there might be something to be said for picking a VP from a swing state in this particular election. But your point it certainly well taken.