From OpenwaterpediaAmerican alligator (Alligator mississippiensis) and the Chinese alligator (Alligator sinensis).
The name alligator is an anglicized form of el lagarto, the Spanish term for "the lizard", which early Spanish explorers and settlers in Florida called the alligator.
A crocodile is not an alligator. Alligators are only native to the United States and China.
American alligators are found in the southeast United States: all of Florida and Louisiana, the southern parts of Georgia, Alabama and Mississippi, coastal South and North Carolina, Eastern Texas, the southeast corner of Oklahoma and the southern tip of Arkansas. The majority of American alligators inhabit Florida and Louisiana, with over a million alligators in each state. Southern Florida is the only place where both alligators and crocodiles live side by side.
American alligators live in freshwater environments, such as ponds, marshes, wetlands, rivers, lakes, and swamps, as well as in brackish environments. When they construct gator holes in the wetlands, they increase plant diversity and also provide habitat for other animals during drought periods. They are therefore considered an important species for maintaining ecological diversity in wetlands. Further west, in Louisiana, heavy grazing by nutria and muskrat are causing severe damage to coastal wetlands. Large alligators feed extensively on nutria, and provide a vital ecological service by reducing nutria numbers.
The Chinese alligator currently is found only in the Yangtze River valley and is extremely endangered, with only a few dozen believed to be left in the wild. Indeed, far more Chinese alligators live in zoos around the world than can be found in the wild.