Merriam's deermouse is a small mouse ranging from southern Arizona into northwestern Mexico. It is recorded in dry scrub, thorn forest, and grassland.
The back ranges from ocher to cinnamon, mixed with dusky hairs; the sides and head are grayish, and the belly is whitish. Some individuals have a dark patch on the chest.
It occurs in dry scrub, thorn forest, and grassland and is often associated with mesquite. Seed-eating and nocturnal activity are described as probable rather than confirmed in the account.
An extinction-risk assessment has not been added yet.