The Six-lined Racerunner (Cnemidophorus sexlineatus) is a species of lizard found in the United States, from Wyoming across the Great Plains east to Rhode Island, south to Florida and west to southern Texas, and in northern Mexico, in Tamaulipas. The Six-lined Racerunner is typically dark green, brown or black in color, with six yellow or green-yellow stripes that extend down the body from head to tail. The underside is usually white in color on females, and a pale blue in males. Males also sometimes have a pale green colored throat. They are slender bodied, with a tail nearly twice the body length.