Odocoileus hemionus, commonly known as the mule deer, is native to North America. Its geographical distribution extends from the western United States, through parts of Canada and down into central Mexico. The species is primarily found in the Rocky Mountains, the western Great Plains, and along the Pacific coastline.

Mule deer inhabit a wide range of environmental conditions including deserts, forests, grasslands, and mountainous regions. They thrive in areas where shrubs and trees provide ample cover and browse opportunities.

The mule deer occupies an ecological niche as a browser, feeding primarily on shrubs, leaves, and twigs, though they also consume grasses and forbs. They play a vital role in their ecosystems by helping to control vegetation growth and serving as prey for various predators such as cougars, wolves, and coyotes.