Crocodylus acutus reaches its northern limit in southern Florida, in the mangrove fringes of Florida Bay, the Everglades and adjacent canals. Alligator mississippiensis reaches its southern limit in the same region. Nowhere else has both a native crocodile and a native alligator.
The two are readily separated in the field. The crocodile has a narrower, tapering snout and shows the fourth tooth of the lower jaw when the mouth is closed, whereas the alligator's broader snout conceals it. Salinity does most of the ecological separation: crocodiles have functional lingual salt glands and tolerate brackish and marine water, while alligator salt glands are ineffective, confining them largely to fresh water.
Florida's crocodile population fell to a few hundred animals by the 1970s and has since increased, supporting a change in United States status from endangered to threatened in 2007. The global species remains Vulnerable, and the Florida recovery should not be read as a range-wide one.