Currently the Sinaloa Martin is considered to be monotypic, but the Sinaloa Martin has had a varied taxonomic history. It has been considered to be conspecific with Purple Martin (Progne subis), together with the taxa dominicnesis (now Caribbean Martin Progne dominicensis) and cryptoleuca (now Cuban Martin Progne cryptoleuca) (Hellmayr 1935); included with dominicensis and cryptoleuca as one of three subspecies constituting the Snowy-bellied Martin (also known as White-bellied Martin) Progne dominicensis, separate from Purple Martin (e.g., Peters 1960, Phillips 1986, Turner and Rose 1989); or together with dominicensis in a species separate from both Purple and Cuban martins (Zimmer 1955). See Systematics.
The taxon sinaloae has been treated treated as a subspecies of Purple Martin (Progne subis); as a subspecies of other species of martin; or as a separate species (see Geographic Variation). An analysis of both mitochondrial and nuclear DNA sequence data across Progne shows that dominicensis, cryptoleuca, and sinaloae belong to a clade of Middle American taxa, together with the Middle American populations of the Gray-breasted Martin (Progne chalybea) (Moyle et al. 2008). Within this clade, sinaloae is sister to the Middle American populations of chalybea, while dominicensis and cryptoleuca are sister to one another. This is, in part, consistent with earlier suggestions of a relationship between sinaloae and chalybea (Zimmer 1955, Eisenmann 1959). Consequently sinaloae is not conspecific with cryptoleuca or dominicensis (contra Zimmer 1955, Peters 1960, Phillips 1986, Turner and Rose 1989).
According to Turner (2004), sinaloae has hybridized with Progne chalybea; we have not traced the original source for this report. Van Rossem (1945) described a specimen that he interpreted as a possible hybrid between sinaloae and Progne subis hesperia: a male specimen from Agiabampo, Sonora (May), that resembled male subis but was small and had "conspicuously white-margined under tail coverts and an occasional concealed white feather on the abdominal region." Davis and Miller (1962) examined the same specimen and concluded that the characters of sinaloae "are very weakly expressed" and that this specimen was best regarded as an "individual variant" of subis.
Within the swallows Hirundinidae, analysis of mitochondrial and nuclear DNA sequence data shows Progne falls within one of the two major clades of swallows; the sister taxon to Progne is the genus of New World rough-winged swallows, Stelgidopteryx (Sheldon et al. 2005).