system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why isn't malaria found in Florida?

There's plenty of malaria in Central America. And there's a canal in Florida that runs from Fort Myers, through the Everglades, across Lake Okeechobee, and on to the Atlantic. It sure seems to me that some mosquito larvae must hitch a ride from time to time.  What's keeping malaria out?  Bonus points for Louisiana and east Texas, too.
gpt
The government (the CDC specifically) actively worked to eradicate it from the US through massive application of DDT. Malaria actually did exist in the southern US until the 1940s.  And if it were to get reintroduced now, it would probably be extremely hard to get rid of again, seeing as we have much stronger environmental sensibilities now than we once did.