The Miles City Intrastate Air Quality Control Region (Montana) consists of the territorial area encompassed by the boundaries of the following jurisdictions or described area (including the territorial area of all municipalities (as defined in section 302(f) of the Clean Air Act, 42 U.S.C. 1857h(f)) geographically located within the outermost boundaries of the area so delimited):
In the State of Montana: Carter County, Custer County, Daniels County, Dawson County, Fallon County, Garfield County, McCone County, Phillips County, Powder River County, Prairie County, Richland County, Roosevelt County, Rosebud County, Sheridan County, Treasure County, Valley County, Wibaux County.