Florida Keys has both, as does at least the Florida Coast from Miami to the Pan Handle. (Atlantic and Gulf of Mexico coasts.) Gulf coast of Mississippi, Georgia, Louisiana, and portions of Texas near/adjacent to Louisiana.
I know for a fact both are also in Tampa Bay. I've seen them with my own eyes, when I was living aboard my then boss' sailboat, at marinas in both Tampa, and St. Pete.

I'm not sure how far north along the Florida east coast from Miami towards Georgia and South Carolina the Gaters and/or Crocks go.
I'm pretty sure at least part of the Mississippi River Delta also has both, as Bull Sharks can (and do) thrive in freshwater. The state of Mississippi has gators.
Bull Sharks have been found in the Mississippi River as far north as St. Louis, MO. Allegedly, the lock and dam in St. Louis keeps them from going farther north.
Personally, I don't buy it. They could go through with one (or more) of the barges or other boats headed north. I suspect the Bull Sharks are in the Mississippi River as far north as Minnesota ... the locks and dams not withstanding. The locks and dams haven't stopped other invasive species. Why would the Bull Shark be the exception?