The West Central Illinois 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 Illinois: Adams County, Brown County, Calhoun County, Cass County, Christian County, Greene County, Jersey County, Logan County, Macon County, Macoupin County, Menard County, Montgomery County, Morgan County, Pike County, Sangamon County, Schuyler County, Scott County.