The USA does have crocodiles as well as alligators.

http://www.tigerhomes.org/animal/curriculums/american-crocodile.cfm

American Crocodiles are very rare in the United States and are only found along the Florida coast in the bay area, in Everglades National Park, and in the keys. Throughout their worldwide range, from Western Mexico to Ecuador along the Pacific, and from Guatemala to Florida along the Atlantic, they live in coastal wetlands. Unlike their alligator cousins the adults can tolerate a saline aquatic environment.

Another comparative difference to the alligators lies in the fact that males will sometime help to guard nesting areas and hatchlings. Adult Crocodiles maintain dens near nest sites… usually a burrow which they dig in stream or creek beds. Unlike the alligators, female crocodiles don't cover usually their eggs with a mass of vegetation but bury them in mounds of soil or sand; some excavate nest holes. Two or more females may share a nest area.