Decker is an unincorporated community in Big Horn County, Montana, United States.

The community is located along Secondary Highway 314, 15.5 miles (24.9 km) north-northeast of Sheridan.

Decker has a post office with ZIP code 59025.

[3] In the late 1930s, the State Water Conservation Board constructed the Tongue River Dam, creating a reservoir just north of Decker.

This Big Horn County, Montana state location article is a stub.