Head and body length of Peromyscus species range from 70-170 mm and tail lengths are 40-205 mm. There are 2 subgenera and 55 species. P. leucopus has soft dense fur and large ears which are covered with fine hairs. The tail is about one third the length of the total length of this mouse, and is also covered with fine hairs. Females have four or six mammae.

The preferred habitat is deep woodlands and brushy areas. Several nest are built each year and are line with soft down from plants or other materials which are shredded. Once a nest is soiled it is abandoned and another is constructed. P. leucopus is primarily nocturnal and active year round, though periods of torpor occur for several hours, during which time there is a drop in body temperature.

They eat seeds, nuts, berries, fruits, insects and other small invertebrates and carrion.

Studies have shown that a paired male and female P. leucopus will live together and that resident females will exclude other females from their home range. Estrous cycles last an average of 5.26 days, gestation periods range from 21-27 days. Litter sizes vary by region, with those in the northern areas being larger. In central Wisconsin the mean litter size is 4.77 offspring.

P. leucopus is found in S Alberta to S Ontario, Quebec to Nova Scotia, Canada; throughout much of C and E USA, excluding Florida; southwards to N Durango and along Caribbean coast to Isthmus of Tehuantepec and NW Yucatan Peninsula, Mexico.