Examination of scalation of American alligators (Alligator mississippiensis) from populations in the eastern and western parts of the species range revealed several scale characteristics that varied between populations and significant variation in the number of transverse ventral rows, number of anterior nuchal scales, number of scales in the anterior dorsal scale row, number of scales in the posterior transverse scale rows, and occurrence of caudal irregularity. Ventral ossification occurs in alligators longer than 165 cm from both the eastern and western parts of the species range. Because of a lack of material from the central part of the alligator's range (Alabama and Mississippi), the nature of this variation cannot be determined.