The Black-tailed Prairie Dog (Cynomys ludovicianus), is a rodent of the family sciuridae found in the Great Plains of North America from about the USA-Canada border to the USA-Mexico border. Unlike some other prairie dogs, these animals do not truly hibernate. The Black-tailed Prairie Dog can be seen aboveground in midwinter. There is a report of a Black-tailed prairie dog town in Texas that covered 64,000 km² (25,000 sq mi) and included 400,000,000 individuals. Prior to habitat destruction, this species was probably the most abundant prairie dog in central North America. This species was one of two described by the Lewis and Clark Expedition in the journals and diaries of their expedition.

Black-tailed Prairie Dogs are generally tan in color, with a lighter colored belly. Their tail has a black tip on it, which is where their name is derived from. Adults can weigh from 1.5 to 3 lb, males are typically heavier than females. Body length is normally from 11 to 13 inches, with a 3 to 4 inch tail. They have small ears, but keen hearing, and small, dark eyes, with good vision.

Black-tailed prairie dogs are frequently exterminated from ranchland, being labelled as a pest. Their habitat has been fragmented, and their numbers have been greatly reduced. Additionally, black-tailed prairie dogs are remarkably susceptible to plague. In 2006, 8 of 8 appearances of plague in black-tailed prairie dog colonies resulted in total colony extinction. Studies in 1961 estimated only 364,000 acres (1,470 km²) of occupied black-tailed prairie dog habitat in the United States. A second study in 2000 showed 676,000 acres (2,740 km²). However, a comprehensive study between 10 states and various tribes in 2004 estimated 1,842,000 acres (7,454 km²) in the United States, plus an additional 51,589 acres (209 km²) in Mexico and Canada. Based on the 2004 studies, the US Fish and Wildlife Service removed the black-tailed prairie dog from the Endangered Species Act Candidate Species List in August 2004.

Black-tailed prairie dogs were the most common prairie dog species collected in the wild for the exotic pet trade until they were banned in 2003. Prairie dogs in captivity at the time of the ban are allowed to be possessed under a grandfather clause, no more may be caught, traded, or sold, and transport is only permitted to and from a veterinarian under proper quarantine procedures.