It is a species of the genus Peromyscus, a closely related group of New World mice often called "deermice".

It is fairly widespread across most of North America east of the Mississippi River, with the major exception being the lowland southeastern United States.

[7] Because the two species are extremely similar in appearance, they are best distinguished through red blood cell agglutination tests or karyotype techniques.

[7] The eastern deer mouse is small in size, only 3 to 4 inches (8 to 10 cm) long, not including the tail.

Deer mice tails are covered with fine hairs, with the same dark/light split as the fur on the rest of its body.

[5] Eastern deermice are nocturnal creatures who spend the day time in areas such as trees or burrows where they have nests made of plant material.

Deer mice that live within overlapping home ranges tend to recognize one another and interact a lot.

[5] Some eastern deermice are found at high elevations where there are low levels of oxygen and ambient temperatures.

They encounter year-round hypoxia and cold, and undergo their entire reproductive cycles under these harsh conditions.

Chronic hypoxia can limit the growth of these high-elevation deer mice during gestation, which can affect development and maternal physiology.

[12] Mouse populations living at different elevations show allelic variation among gene duplicates that encode the α-chain subunits of adult hemoglobin.

[12] Modifications in the α and β globin genes may also indicate an increase in hemoglobin-oxygen affinity and oxygen transport in these high-elevation populations.

[15] Female deer mice construct nests using a variety of materials including grasses, roots, mosses, wool, thistledown, and various artificial fibers.

[17] In a study, less than half of both male and female deer mice left their original home range to reproduce.

This phenomenon is typically shown in their abnormally large nest sizes and the behavior is present within 8 weeks of birth.

[14] Deer mice pups are altricial, i.e. born blind, naked and helpless; development is rapid.

[26] Deer mice, specifically the prairie form, are also abundant in the farmland of the midwestern United States.

[29] Deer mice are often active in open habitat; most subspecies do not develop hidden runways the way many voles (Microtus and Clethrionomys spp.)

During the fall season, the deer mouse will slowly change its eating habits to resemble the winter's diet.