Eastern:
T. c. oberholseri (Law, 1928) – Brownsville thrasher.
Generally ranges from SE Texas to NE Mexico (E Coahuila, Nuevo León and Tamaulipas).

T. c. curvirostre (Swainson, 1827) – Ranges from Central to South-Central Mexico (towards Pueblo, Oaxaca, and Veracruz).

T. c. celsum (R. T. Moore, 1941) – plateau thrasher.
Range spans from SE Colorado, SW Kansas, extreme NW Oklahoma to S/SE Arizona, S New Mexico and W Texas to Northern Mexico (E Chihuahua to Guanajuato and Jalisco).

Western:
T. c. insularum (van Rossem, 1930) – San Esteban thrasher.
Located in the Islands of San Esteban and Tiburón off the coast of Sonora in the Gulf of California.

T. c. maculatum (Nelson, 1900) – spotted thrasher.
Found in NW Mexico (S Sonora, N Sinaloa, SW Chihuahua).

T. c. occidentale (Ridgway, 1882) – Mazatlan thrasher.
Located in Western Mexico (from Sinaloa and Nayarit to Jalisco).

T. c. palmeri (Coues, 1872) – Palmer's thrasher.
Range is S Arizona, N Sorona and Chihuahua.
This species is the representative of the western species, and was suggested to have enough variations to be considered a different species from T.c.
curvirostre.
T.c.
palmeri was also used in a 2009 proposal by the American Ornithologists' Union to be elevated to species status, along with the eastern T.c.
curvisrostre representing the eastern curve-billed thrashers.
Eastern:
T. c. oberholseri (Law, 1928) – Brownsville thrasher. Generally ranges from SE Texas to NE Mexico (E Coahuila, Nuevo León and Tamaulipas).
T. c. curvirostre (Swainson, 1827) – Ranges from Central to South-Central Mexico (towards Pueblo, Oaxaca, and Veracruz).
T. c. celsum (R. T. Moore, 1941) – plateau thrasher. Range spans from SE Colorado, SW Kansas, extreme NW Oklahoma to S/SE Arizona, S New Mexico and W Texas to Northern Mexico (E Chihuahua to Guanajuato and Jalisco).
Western:
T. c. insularum (van Rossem, 1930) – San Esteban thrasher. Located in the Islands of San Esteban and Tiburón off the coast of Sonora in the Gulf of California.
T. c. maculatum (Nelson, 1900) – spotted thrasher. Found in NW Mexico (S Sonora, N Sinaloa, SW Chihuahua).
T. c. occidentale (Ridgway, 1882) – Mazatlan thrasher. Located in Western Mexico (from Sinaloa and Nayarit to Jalisco).
T. c. palmeri (Coues, 1872) – Palmer's thrasher. Range is S Arizona, N Sorona and Chihuahua. This species is the representative of the western species, and was suggested to have enough variations to be considered a different species from T.c. curvirostre. T.c. palmeri was also used in a 2009 proposal by the American Ornithologists' Union to be elevated to species status, along with the eastern T.c. curvisrostre representing the eastern curve-billed thrashers.
Curve-billed thrasher