40 C.F.R. § 81.39
The Metropolitan Dallas-Fort Worth Intrastate Air Quality Control Region (Texas) has been revised to consist 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 Texas: Collin County, Cooke County, Dallas County, Denton County, Ellis County, Erath County, Fannin County, Grayson County, Hood County, Hunt County, Johnson County, Kaufman County, Navarro County, Palo Pinto County, Parker County, Rockwall County, Somervell County, Tarrant County, Wise County.
40 C.F.R. §81.39