When I did a Google search the top three rat stories were all in Florida. This makes sense as there is warm weather a lots of vegetation. Both in Florida and the Bay Area the main problem rat is the roof rat, Rattus Rattus, as opposed to the norway rat. The norway rat is the usual city or sewer rat. The roof rat is agile and acts much like a squirrel.
And here is a map to show where the roof rat lives:
And you can see why Florida and much of Texas is prime rat country.