40 C.F.R. § 81.117
The Southeast Missouri Intrastate Air Quality Control Region 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 Missouri: Bolinger County, Butler County, Cape Girardeau County, Carter County, Crawford County, Dent County, Dunklin County, Gasconade County, Iron County, Madison County, Maries County, Mississippi County, New Madrid County, Pemiscot County, Perry County, Phelps County, Reynolds County, Ripley County, St. Francois County, Ste. Genevieve County, Scott County, Stoddard County, Washington County, Wayne County.
40 C.F.R. §81.117