Females are larger with a significantly longer forearm.
This species occurs throughout much of western North America, from central Mexico to extreme northwestern British Columbia and from the Pacific Coast to the western margins of the Great Plains. It is a commonly encountered bat. The long-legged myotis is primarily a coniferous forest bat also found in riparian and arid habitats in some areas. They may also shift habitats seasonally. It uses a variety of roosts including abandoned buildings, cracks on the ground, crevices, and spaces beneath tree bark.