The map of Florida counties gives lie to the I-4 corridor fantasy.
Note that at one end lie Hillsboro and Pinellas and at the other Orange and Osceola, counties that voted Democrat for Obama.
In the middle, the vast Southern Baptist stretch of pasture voted Republican for McCain. Polk, Lake, Pasco, and Sumter counties lie to each side of I-4 between Tampa and Orlando.
If you want to see I-4 as a lever for change for the Republican party in the past, the current configuration is a better description.
It resembles a dumbbell.
The I-4 dumbbell... Yes, it has a ring of truth.