Other Scientific Names
Aimophila cassinii [(Sibley and Monroe (1990, 1993)], Aimophila cassinii [Stotz et al. (1996)], Aimophila cassinii [BirdLife International (2004, 2008)]
Breeds from central and southern USA (south-western South Dakota, central Wyoming, eastern and central Colorado east to west-central Kansas, and central Oklahoma, south to south-western New Mexico, and southern Texas) and northern Mexico (south to northern Chihuahua, southern Coahuila, Zacatecas, San Luis Potosí, and south-eastern Tamaulipas). Non-breeding south-western USA (south-eastern Arizona, south-western New Mexico, western Texas, possibly also eastern Nevada) southern in Mexico to southern Sinaloa, San Luis Potosí, northern Nuevo León and northern Tamaulipas, rarely to Guanajuato.
 
Rarity Status
Currently this species is not classified as a rarity in this country OR information has not been updated.
Population
Estimated population is 20,000,000 (2010).
Cassin's Sparrow (Peucaea cassinii) [XC511052]
by Bobby Wilcox from Santa Margarita Ranch, Pima County, Arizona, United States (song)
Cassin's Sparrow (Peucaea cassinii) [XC611285]
by Richard E. Webster from Las Cienegas National Conservation Area (Empire Gulch), Pima County, Arizona, United States (song)
Subspecies
No subspecies.
Formerly placed in Aimophila, but molecular-genetic studies indicate that such treatment would make that genus polyphyletic. Closely related to Bachman's Sparrow (Peucaea aestivalis) and Botteri's Sparrow (Peucaea botterii), all having aerial song displays. Molecular analyses suggest that this group is close to a clade consisting of Stripe-headed Sparrow (Peucaea ruficauda), Black-chested Sparrow (Peucaea humeralis), Bridled Sparrow (Peucaea mystacalis), Cinnamon-tailed Sparrow (Peucaea sumichrasti) and Rufous-winged Sparrow (Peucaea carpalis).