Oh, that's a good one! Honestly I forgot key limes are a Florida thing, having lived all over the U.S. I've never experienced any issues getting my hands on key limes or their pie, so they're definitely available and popular nationwide. I can go grab both from my local Safeway on the complete opposite end of the country.
That reminds me that oranges used to be THE Florida thing as well, before citrus canker wiped them out in the 90s. Now all Florida Orange Juice^TM is from California.