Tropical Gar are from central America...thats about as close as your going to get. And then theres the Cuban gar and I'm sure you can guess where that one's from. The rest are from North America.
Atractosteus spatula and Lepisosteus oculatus / platyrhincus have been found as released pets or illegal introductions in some portions of the Amazon. None however have ever been established as far as is known.