South-western USA and Mexico, from California, Utah and Colorado eastern inland to Missouri and Louisiana, through coastal Texas and Baja California, south to Michoacan, Puebla and Veracruz.
 
Population
Estimated population is 1,100,000 (2010).
Greater Roadrunner (Geococcyx californianus) [XC163983]
by Richard E. Webster from west end of Monument Rd, Tijuana River Valley, San Diego Co, California, United States (call, billed snapping)
Greater Roadrunner (Geococcyx californianus) [XC611013]
by Richard E. Webster from Whitewater Draw WA, near McNeal, Cochise Co, Arizona, United States (song)
Subspecies
Population from Texas (USA) south to Nuevo Leon and Veracruz (Mexico) averages smaller and has been described as subspecies dromicus, but birds from this region overlap in size with those in other parts of range.
No subspecies.
Similar Species
Like Lesser Roadrunner (Geococcyx velox) but underparts streaked.
References
See References.