Systematics

Corvus impartus is monotypic.

Early authors (e.g. Ridgway 1904) used the name Corvus mexicanus for Tamaulipas Crow, based on Corvus mexicanus Gmelin 1788. Peters (1929), however, documented that Gmelin's "crow" referred to Quiscalus mexicanus (Great-tailed Grackle), and so the Mexican Corvus lacked a name; Peters (1929) then described this species as Corvus imparatus, with a type locality of Rio La Cruz, Tamaulipas, Mexico.

For many years it was believed that there was only taxon of crow in Mexico, occurring in both the northwestern and northeastern regions of the country (e.g. Ridgway 1904, Peters 1929, Miller et al. 1957). Davis (1958) pointed to vocal differences, and slight morphometric differences, between these two populations, and described the crows of western Mexico as a separate species, Corvus sinaloae (Sinaloa Crow). Most authorities have accepted sinaloae as a species, although Johnston (1961) recognized sinaloae as only a subspecies of imparatus.

Corvus imparatus long was considered to be a southern representative of Corvus ossifragus (Fish Crow) of the eastern United States (e.g., Hardy 1990). Hellmayr (1934) went so far as to consider imparatus "clearly conspecific" with ossifragus, and Blake (1953) also classified imparatus as a subspecies of ossifragus. Phylogenetic analysis of DNA sequence data, from both nuclear and mitochondrial genes, confirms that imparatus and sinaloae are sister taxa, and that these two in turn indeed are sister to ossifragus (Jønsson et al. 2012). The ossifragus/imparatus/sinaloae clade in turn is sister to Corvus palmarum (Palm Crow) of the Greater Antilles (Jønsson et al. 2012).