The eastern indigo snake has a blue-black colour. It is the longest native snake species in the United States. Males usually grow up to 1.58 m (5.2 ft) in length. Females usually grow up to 1.38 m (4.5 ft) in length. Males usually weigh 2.2 kg (4.9 lb). Females usually weigh 1.5 kg (3.3 lb).