40 CFR § 81.44 - Metropolitan Memphis Interstate Air Quality Control Region.

The Metropolitan Memphis Interstate Air Quality Control Region (Arkansas-Mississippi-Tennessee) 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 sec. 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 Arkansas: Crittenden County.

In the State of Mississippi: De Soto County.

In the State of Tennessee: Shelby County.