The genus has a cosmopolitan distribution, with native species on all continents except Australia.

Most are found in North America.

[2] Hosts of Dermacentor ticks include many large and small mammals, including horses, deer, cattle, lagomorphs, peccaries, porcupines, tapirs, desert bighorn sheep, and humans.

[2] The American dog tick (D. variabilis) is a member of the genus.

[3] Dermacentor species are vectors of many pathogens, including Rickettsia rickettsii, which causes the disease Rocky Mountain spotted fever, Coxiella burnetii, which causes Q fever, Anaplasma marginale, which causes anaplasmosis in cattle, Francisella tularensis, which causes tularemia, Babesia caballi, which causes equine piroplasmosis, and the Flavivirus that causes Powassan encephalitis.