Buff-collared Nightjar occurs from the southwestern United States south to Honduras and Nicaragua. In the United States the distribution is confined to southeastern Arizona and extreme southwestern New Mexico (Bowers and Dunning 1997). In Mexico is occurs south, primarily along the Pacific slope but also in the Balsas drainage, from Sonora and western Chihuahua to Chiapas (Friedmann et al. 1950, Binford 1989, Howell and Webb 1995). There also is an isolated population in central Veracruz (Howell and Webb 1990). The distribution continues south through central Guatemala and Honduras to south central Nicaragua (Monroe 1968, Land 1970, Martínez-Sánchez and Will 2010).
Buff-collared Nightjar is resident north to southern Sonora, Mexico. Populations in the United States and in northern and central Sonora are migratory. They probably are present in this region only from May through August (Howell and Webb 1995), although at one site in south central Sonora Buff-collared Nightjar is reported from 8 March-15 October (Russell and Monson 1998).
The elevational range of Buff-collared Nightjar is from the lowlands up to 1800 m (Howell and Webb 1995) or to 2000 m (Parker et al. 1996).